If you're shopping for a guitar, the best way to find out what guitar is best for you is to go into a store and play them. I recommend a Guitar Center or Sam Ash if you have one nearby. If not, most any guitar shop or even a pawn shop will do for just trying out stuff.
Don't feel embarrased to pick one up, even if you don't how to play yet. Hold it in your hands and see how the neck, the strings, and the frets feel. When you're first learning, comfort and playability trumps quality of tone or finish.
If you're looking online,
Musiciansfriend.com has great prices and a very lenient return policy. Here's a few starter packs that include a guitar, small amp, strap, picks, strings, tuner, and other goodies to get you started.
Behringer V-Tone II - $109.99
http://www.musiciansfriend.com/srs7/g=guitar/search/detail/base_pid/511681/
Since you're on CAG, I'll assume you want the cheapest first. Behringer is a quality name in sound equipment and this pack is an unbelievable value. The guitar is a strat copy, so it should play just as well as the squire guitars. The only thing is you'll have to pay shipping on it, which came to about $11 for me.
Fender Squire SE-100 Pack - $199.99 w/free shipping
http://www.musiciansfriend.com/srs7/g=guitar/search/detail/base_pid/511681/
If you simply must go with a Fender (Squire is a sub-brand of Fender guitars, usually made in Asian countries on machined assembly lines) go with this pack. The guitar is the same as the Squire Strat pack, but the amp is slightly less beefy, but you probably wont notice the difference (10W vs. 15W)
Fender Strat Pack - $279.99 w/free shipping
http://www.musiciansfriend.com/srs7/g=guitar/search/detail/base_pid/519633/
This is virtually the same as the package above, but includes a 15W amp with some auxilary inputs for a CD/MP3 player so you can play along with it.
This pack is also what you are most likely to be sold at any given music shop as a beginner.
Epiphone Les Paul Special II Pack - $229.99 w/free shipping
http://www.musiciansfriend.com/srs7/g=guitar/search/detail/base_pid/518677/
If you prefer the Gibson/Epiphone guitars (humbuckers = fatter tone), this pack is a good value. I personally owned one of these guitars when I started and loved playing it.
As for sheet music, most music shops sell it, either by the song or by the book, which usually contains a complete album or collection of songs.
As a beginner, you would probably find tabs (short for tablature, where numbers indicate the fret and string to play, vs reading music notes on a staff) easier to read and play by. There are many sites online you can get free tabs for popular songs, including:
A great tutorial on reading and playing by tabs:
http://www.harmony-central.com/Guitar/tab-notation.txt
http://www.olga.net
http://www.tabcrawler.com
http://www.mxtabs.net
http://www.guitaretabs.com
http://www.ultimate-guitar.com
http://www.guitartabs.cc
or just do a google search for the name of the song + tabs
I hope this helps and I hope you enjoy playing guitar. Feel free to PM me if you need some advice or help with anything. It will take a lot of practice and patience to get good, but it is well worth it to hear yourself jamming on your favorite songs, or playing something for someone else.