Any Brewers out there want to lend some advice to a 1st time beer maker

I am pretty damn good at drinking beer but I have no idea what I am doing making beer. My girlfriend bought me one of the MR Beer beer kits so I am giving that a try today. I am going to use one of their beers that is all setup where all I have to do is sterilize the utensils/beer vat thing, add a can of some crap and a bag of some crap to water and let it ferment. After I do this though I would like to get into it some more and try my own stuff. A couple questions

1) can I use the beer keg thingy for future beer good enough or is it just not going to cut it? If not what do I need?

2) where do you buy the ingrediants that go into beer making if you aren't just using this kit stuff?

Really, I would love to hear about anybody else's experiences, tips, etc...