ok, gexgex, I’m mostly rehashing what’s already been said, but in the true American spirit, I’m going to throw in my two cents worth. Besides, since I graduated in June(WHOOOO!) I think I’m fairly qualified to answer most of these.
sorry if the responses are a little disjointed.
WARNING! INCREDIBLY LONG POST!
ok, American Pie, and Ten Things I Hate About You were fun movies, and Clueless…I suppose it had it’s merits…maybe… but they were as true to real American high schools as Crocodile Dundee probably was to day-to-day life in Australia.
do you have proms? yes, they’re quite common. usually a club or a class takes over the decoration and organization of the dance. Most are held at the end of May when the weather warms up–just the right temperature for us girls to suffocate in our poofy dresses. and yes, many girls wear the typical horribly expensive cotton-candy colored gowns. Personally…yuck. How are you supposed to party when you need an extra chair for your skirt?
are they as exciting as the movies make out? NO. no live bands, or if they are, they usually suck. no disco ball. (ok, maybe a disco ball, but we’ve never had one.) They’re sometimes held in the gym, sometimes the Prom committee rents a hall; it depends on the school, the budget, weird school traditions, etc. Sometimes a Prom King and Prom Queen are “elected”, and it is usually a popularity contest, but (at my school at least) it’s sort of goofy, and the “positions” aren’t nearly as coveted as they are in the movies.
rmariamp covered corsages–they’re ok, but IMHO, a little old fashioned. They’re usually made out of roses or carnations.
does anyone go to the prom if they don’t have a date? sure! all the time. Proms are just a big party, after all. I didn’t go to my prom, because I was in a “Fight The Establishment!” mood, and other reasons–but no, a girl or guy who “goes stag” won’t be ostracized. and to set another record straight: There is a distinct lack of post-prom drunken orgies in the back seats of cars. Want to know what my best friend and her boyfriend did after the prom last year? They went mini-golfing…or at least, that’s what she told me…
do you have cheerleaders? yeah, and they do actually jump up and down in those bright uniforms with short fluffy skirts (the style shown in movies is actually pretty accurate) and cheer on the boys’ football, basketball, and sometimes baseball teams. sadly, there is quite a shortage of hot guy cheerleaders for the girls’ teams.
are they all perky and stupid (brittany from daria)? Most are perky, I guess. But to jump around in a tight purple and yellow uniform, you’d have to be. There are ditzy people everywhere, but few of the cheerleaders that I know are stupid–half of the squad at my high school were honor students.
are said cheerleaders universally hated by all? Not really. The Hollywood cheerleader image is way off. (again, my experience is limited to one urban high school) People who’re self-centered just because they giggle and show their tush at football games wouldn’t be very popular. Most I know are pretty cool, though. They’re genuine athletes, with rigorous practices, and are required to master complex gymnastics.
are footballers idolised? well, we don’t say “footballers”. we just call 'em football players. and they’re not anymore “idolised” than any other high school sports team.
do they all have cheerleader girlfriends? nope. but FYI, we do actually have “varsity” jackets. The name’s probably traditional, because you don’t have to be on the varsity football team (read: be one of the best, most experienced players) to get one–they’re usually a fundraiser for the sports department. If you want to shell out the cash, it’s yours.
do you have a fashion club, and do you watch all your movies from projector reels? A fashion club? Not at my school, but hey, if a bunch of students wanted to start one, the administrators would probably ok it. If they didn’t the principal would probably have a petition on his desk in a few weeks detailing exactly why the club should be allowed to meet on school property, how the students would benefit from the increased interest in extracurricular activities, etc. most American HS students are beatniks and activists at heart 
I haven’t seen a projector reel since those lame movies the librarian showed in my elementary school. Some teachers use overhead projectors in their lessons, but if we’re going to watch a movie, educational or otherwise, we use a TV and VCR.
does every school really have a cool popular kid - with a big house and cool parents - who has cool parties? But of course! Hollywood stole the idea from me! 
seriously, no. at least not in most lower-middle class neighborhoods.
are drama students not cool? nope, that’s another myth.
do you have a lunchroom, and how often do you eat there? is it really disgusting? some schools offer breakfast, but most people only eat lunch there, and yes, the food is horrifying. The older you get, the worse the food is. Or maybe your tastebuds aren’t fully developed in elementary school. Whatever the case, I packed my lunch for 4 years straight, except for those dismal mornings I slept late, and had to face the lunch line. Many American schools have vending machines in their cafeterias, which has become the subject of national debates. The kids obviously prefer Pepsi and pretzels to the “goop du jour”. The cafeteria food may be kind of gross, but it’s got more nutritional value than a twinkie.
can you be socially isolated by not sitting with certain people in the lunchroom? The hierarchy usually isn’t that strict. most people just sit with their friends, who may or may not be in the same club, or the same race, or the same…whatever.
are all the teachers weird? Really, sometimes you win, sometimes you lose. For instance, last year, my sociology teacher was very cool, and I learned a lot. My Spanish teacher, however, was a total nutcase.
is gym class scary, and why don’t you call it p.e? Well, I wouldn’t call it scary, unless the mean, tatooed football coach substitutes… and sometimes we do call it P.E., it’s just not as generally used. I suppose it’s called “gym” because it’s in the gymnasium. I never really thought about it.
what’s the deal with school uniforms? why don’t you have them? oooh, school uniforms… a few public schools have them, or are trying them on a trial basis. Private and parochial schools usually do. Most public schools have dress codes: our school forbade shirts showing the navel, sleeveless shirts, flip-flop sandals, nylon jogging pants, and hooded shirts. Believe it or not, this has been a growing political matter in the past…decade or so, I’m guessing. There have even been court cases and lawsuits on this subject. I’d say most high school kids are against uniforms, just because we like having our own stuff. Besides, those blue wool skirts I see on the girls at the little Catholic elementary down the street look like they itch, big time.
do all students have really cool cars? yes, everyone who’s anyone drives a Porsche. The rest of the riff-raff have to settle for BMWs 
no, we don’t. one or two kids might, but they’re the exception–and most of the exceptions have worked their butts off to pay for them. I don’t know whether a larger percentage of American teenagers have cars (I’m guessing yes), but most kids get really cheap POS cars (Piece Of Shit, in case you’re wondering) (or “beaters”) that they can pay for with money saved from a part-time job. I know few people whose parents bought them a car. Some don’t bother. I didn’t (and still don’t) have a car, and I haven’t bothered with my license.
me being 18, doing my final year of high school - what would i be doing were i an american? would i be in college, would i be a high school senior, what? one of those. depends on when your birthday falls. I’ll be 18 next month, and I’m starting college, but some of my friends turned 18 at the beginning of their senior year.
is it at all safe to attend an american high school or is it a haven of firearms? school violence isn’t all that common.
the Starbucks thing is sort of a nationwide inside joke, because they are everywhere, they are expensive, they are packed, and yes, they are disgusting.
are all the aussie bands that we get told are ‘making it big in america’ really gaining any decent exposure? for instance, have you heard of silverchair, savage garden, the living end, the avalanches or frenzal rhomb?
Savage Garden is one of my absolute favorites! I’ve heard of Silverchair, but I haven’t heard of any of the others.
and as far as Australian girls, I’m straight, so I couldn’t tell ya. But I have to go along with the crowd: a male Australian accent is incredibly hot.
ok, I think I’ve done enough posting for a few weeks right here. bye!