Hi and welcome!
Don't be overwhelmed. There is a lot of info to digest, but really, raising chickens isn't all that hard.
If you are interested in meat birds, go to the meat bird section and read through the threads there. You'll find a lot of interesting stuff.
I don't actually raise meat birds. We do eat the occasional extra rooster from our laying flock. And the meat is great! I can only imagine that a bird that was actually bred to be a meat bird would be even better.
I think that most folks who raise meat birds raise the Cornish Crosses. If I ever do it, I will go with the Dark Cornish. Maybe a mistake, but I like the idea of having a flock that can sustain itself. Plus, I like the look of them. Very hawkish and wild looking. Pretty birds, in my opinion.
If you are looking for a laying hen that will be big enough to make a nice table bird after her laying days are over, maybe a Sussex or an Orpington would be a good breed to consider. I have a couple of Buff Orps, and they really are large ladies! I expect that any of the dual purpose birds would have less breast meat than the chickens you buy at the grocery store.
I guess how many you should get depends on your situation. How much room do you have, how much meat do you want to put in the freezer, etc. Also consider any local ordinances that you may have regarding poultry.