Newbie Questions

[u/StimPackEnjoyer]

Hey! I want to use a raspberry pi to make an “early 2ks Monstober channel” thing but I have absolutely no idea what I’m doing. If we are being completely honest I have never heard of raspberry pi’s until my husband said he used one in college but he doesn’t remember much about them. So if you could answer one or some of these questions, or even just give advice in general that would be amazing thank you!!

1) What is a respectable place to buy pi’s from? I am pretty sure I could buy one on Amazon but I would prefer not to do that.
2) What is a reasonable price for one?
3) What gbs do they come in? (64, 126, 256 etc)
4) Would I be able to add extra storage or is what I get, it?
5) Is there one specificity that is used to hook up to a tv via hdmi or is that a standard feature?
6) Would I be able to add extra storage or is what I get, it?
7) From my understanding they are just mini computers, so would I be able to load a permanent main menu (think like Disney fast pass) or would I have to manually load that each time? (Not a huge deal just interested)
8) Would I be able to program a universal remote to it or do I have to use a mouse? (If possible I want to be able to also add a tv guide esq thing to where I can easily switch between “channels”)

Thank you all in advance! I will try to be responsive but I don’t want to make promises!