1. so once I 'sell' the address to you, am I able to use that address afterward?
No worry about noob questions. You aren't born knowing this shit and honestly I've learned new crypto shit every day since 2012 almost.
You can reuse the address afterwards, but it wouldn't be very "crypto" of you. You can also dig/sell none empty addresses if you so wish... again though that wouldn't be very crypto of you.
I strongly strongly strongly recommend retiring the address after you share your private key.
The best kept secret is.... your own secret . This way if your computer gets hacked or something you can't say "well maybe it was that bastard BAC!"
We want to keep trust out of the equation as much as possible and whenever we can!
If you have any more questions please please please feel free to ask. There are no bad questions, only bad people! jk
final question, where can I find out my private key?
I am using blockchain
EDIT: all good, just done and waiting for my payment