Boy, talk about over estimation. It was more like 11 miles. Still, I suppose that’s not too shabby for not having been on a bike in twenty years.
Nothing wrong with a hybrid bike. Mine is nimble and light and useful around town, as you said. I’ve done two sprint tri races on one and finished at an above average time.
OK, that’s a sprint triathlon.
I suggest building up a nice base-- that is, where you can do 20 -25 miles regularly iwthout problems and then do interval training. Pick a safe, comfortable route of about 1/2 - 3/4 mile and ride as hard as you can at very high cadence (at least 100) in one direction, then easy peddle back. Repeat 4 or 5 times. Or, if you have a comfortable loop, you can do the same thing without backtracking.
The week before the race, take it easy. Just do some comfortable, short rides and easy run.
Beware of the swim. It’s short, but it’s likely to be a madhouse. Find a comfortable place off to the side so you don’t get mauled. The swim is going to be the shortest leg of the race. As my friend used to say: The race begins when you get out of the water.
And now my bottom is sore.
Get some Bag Balm and more saddle time.
Are you wearing proper padded bike shorts? Makes a big difference. 
11 miles in 45 minutes is a decent pace, especially for someone who hasn’t been on a bike in years. Did you get it set up for your body properly? I second (or third?) the advice on clipless pedals - you’ll see a huge increase in efficiency by doing this.
If you go clipless. you MUST practice. Find a soft area and just ride around while clipping in and unclipping. The unclipping motion is not a natural one. You twist your heel outward to unclip. The normal reflex when stopping is to try to pull the foot straight back, leaving the foot attached to the pedal and you approaching the ground quite rapidly.
I’m getting the bike properly fitted on Friday. The mechanic was on vacation until Tuesday.
For those of you keeping score at home, I’d gotten a Giant Escape. I’m still astounded as to how light it is. I grew up on a Schwinn hunk of steel. The trigger gears are nice to work with. They’ll be even better once it’s been fitted. They tend to click right now.
I haven’t read all the post so I’m probably repeating things.
If you want to compete, you need at least a road bike. A dedicated Tri-bike would be better, but they are a pain to ride. Lance Armstrong would have trouble competing in a Tri using a hybrid, even with aerobars, no matter what drugs he was using.
I am wondering about the practicality, for racing, of putting on an 11-speed cassette in favor of dropping a chainring and the front derailleur (saving maybe as much as half a pound). Not really so much for the weight savings but because it is a tremendous advantage to be able to track straight through the gear range (an 11-32 cassette provides plenty of range for pretty good hills).
This is intended for Mt. bikes, but you could give it a try.
It’s amusing how much time, energy and often $$$ people will spend on shaving a few ounces (sometimes less) off their bike when they are 20, 30, 40 + pounds overweight. You want to go up that hill faster and easier? Train more and lose some weight! 
Not saying you’re fat,** For You**. I have no idea what condition you’re in. Just that it’s not an uncommon scenario.
It’s a fine bike for your first tri. Don’t worry about it.
I personally know someone who on the very first sprint distance triathlon came in first in the age group 35-40, on a non-suspension mountain bike with slick tires and no aero bars.
This is so much more about your training and effort you put into that than the equipment you’ll be using.
I, personally, am not a “weight weenie”, my Bacchetta Giro weighs around 30lbs with its somewhat draggy but very quiet Nuvinci 360, my StreetMachine GTe a few more than that. My main interest is having straight-line shifting, because going from gear-to-gear quickly, up the line, improves acceleration a lot.
And Maus Magill appears to be in pretty good shape, weight might come to matter to him (and maybe that wisp of drag the FD, cable, etc create).
And to we who ride 'bent, it is not “fat”, it is an “aerobelly”.
When it comes to weight and what not, I’m not too worried. I think I could shave the more weight off me than I could on the bike.
Cost benefit analysis indicates, I would shave more weight for a lower cost by (shudder) avoiding potato chips.
I think that’s the right attitude. Good luck with your training. Come back and share your race results and experience.
so he can do about 15 miles per hour. just curious, what would his speed be if it were a $1000 bike?
$1000 bike?.. 15mph
$3000 bike?.. 15mph
$7000 bike?..15.1mph
$10,000 bike?..160mph. If he was pushed out of a plane.
A $1000 hybrid, probably not much different.
A $700 road bike, probably a few MPH faster.
Having ridden long rides on both a hard tail mountain bike and skinny tires and a road bike the difference is striking.
The difference was several MPH and a huge difference in effort.