LOL well I think most of us started that way. I DUNNO ANYTHING ABOUT THEM BUT I WANT CHICKENS!!!
Some chicks can be sexed at birth, suck as Barred Rocks I believe.
I have 5 pullets that just started laying and 5 2.5 year olds and I get way too many eggs. I would say 5 would be a good number for you. But hatch rates are not guaranteed, so maybe get 10 or 12 and if you end up with extras, sell them locally. Better to have too many than not enough seems to be a lot of forum members mottos LOL!!!
Welcome to the crazy world of chickens.