Hello, neighbour!  
I strummed chords on an acoustic guitar for a while, and I’ve just recently decided to learn how to play electric.  The acoustic is a Takamine C-128 classical guitar I bought 25 years ago.  People who can actually play say it sounds great.
In my madness I’ve bought a '93 Fender Telecaster, built a Telecaster out of 2008 American Fender parts, a Squier (by Fender – And yes, they spell it that way) Telecaster, and an Epiphone Les Paul.  Here are my electric guitar newbie impressions:
Fenders are expensive.  If you buy a new or ‘vintage’ American one, they’re about $900 and up.  Mexican-made ones are $450 or so at the local guitar shop.  As a new user, they sound fine to me.  More experienced players such as squeegee and Wordman are much more discerning than I; but for me the cheapest ones are fine and fun.
Even as a newbie, I can tell the Squier is not great.  But they’re cheap, so you’re not risking much.  I have an idea that a Squier would be fine to learn on, and that your next guitar would be more appreciated when you hear the difference.  I think a Squier would be acceptable for family sing-alongs.  (I’m modifying mine to sound more like a real Fender.)
Epiphone is Gibson’s ‘bargain brand’, but they were being made for decades before Gibson acquired them.  (Squier is Fender’s in-house bargain brand.  There’s no such thing as a pre-Fender Squier.)  Several well-known musicians including John Lennon and Paul McCartney have chosen Epiphones.  Mine, which I just got on Friday, sounds great.  It’s heavier than the Telecasters and has a richer sound.  (My FrankenCaster sounds close, with its upgraded pick-ups and 4-way switch.)  The model I bought goes for about $450 new, which is about the same as a Mexican-made Fender and about three times the cost of a Squier.  But you get the Gibson sound for a fraction of the price.
When I was looking at electric guitars I checked the local pawn shops.  Selection was not great, brands tended to be lower-rung, and prices weren’t all that great.  The one I remember is a used Squier for $150, while you can buy a new one for about $160-$190.  Pawn shops in larger cities will have a better selection.
eBay has many guitars.  One thing about auctions is that when there is a large selection you’ll usually pay market price, unlike a pawn shop where they often overcharge.  I’ve seen some Epi Les Pauls that were damaged in shipping; heads broken off.  You might pick one up and repair it with good wood glue and a clamp.  You can save some money that way, but you’ll need to fix it.
I haven’t tried to connect the amp to my Mac.  I assume there are adapters, but my little 15w amps don’t have Firewire or USB or anything.  You could always just set up a microphone.  If you are thinking of an acoustic guitar then you’d use a microphone.  Or, you can get an acoustic pick-up and plug it into an amp and use the presumed adapter to connect it to the computer.
Those are my newbie impressions anyway.