Stringing the guitar: check from about 2:10 in
this
When you're close to the tone you're tuning to, come from below the note, rather than going higher than the note then tuning down - it stays in tune longer and the string's stronger.
If you're really new to the guitar, don't bugger about with drop C - absolute fidelity to the pitch isn't really necessary if you're just fannying about in your bedroom. Plus, if you've got anything other than really thick strings, it'll sound like utter crap, because they'll rattle against the neck like nobody's business.
If you're breaking strings, try a thinner plectrum. To start with, your plectrum technique won't be great, so a thicker plectrum will really take it out on the strings. Hence breakage. Thinner plectrums are better for strumming as well, and to start with that's all you really need to do. If you're still breaking strings, try playing closer to the neck of the guitar - playing near the bridge is where the strings are most taut, so applying pressure there will both de-tune the strings and lead to them breaking.
Remember that everyone who works in a guitar shop is a cunt. But even so, if you're asking them questions, make sure you point out you're an absolute beginner. They'll try and baffle you with bullshit, but if you don't understand what they're talking about, just say so. They'll huff, but it's their job to deal with beginners, not to be treat people like idiots. I've been playing guitar for 13 years now, and I still haven't the slightest idea about the strange language guitar shop people speak. I have all my guitar bits delivered to me by a mate who works in a guitar shop because I actually can't tolerate being near guitar shop people.
Uh... that's probably quite a bit of information. PM me if you're after any more tips n' stuff.