#1) Great! Welcome! The problem isn't you, its the spam bots and account farmers. Put up with it for a little bit, and it'll get easier.
#3) What are you talking about? Signature advertisements?
#4) No... I don't think any moderator would buy an account. It is OK based on the rules, but people will probably think its untrustworthy behavior and give you negative feedback for doing so.
The Rest) Use escrow to avoid scams, and walk away from any deal that seems too good to be true, or requires you to do anything you don't feel is right or safe. There is no reason to trust someone with your money, especially when you are using a semi anonymous non reversible currency.
As for point B
B. Just because MODS act sketchy, doesn't mean that Newbies can. They can see the admin panel and tell where users IPs are from and safely avoid scammers from third world countries that use clamshell phones for Internet access. Countries like the People's Republic of Bumblefuck.
What mods are acting sketchy? Also, no we can't see any IPs, and even if we could the scammers in third world countries you are talking about are probably using Tor or VPNs, so it wouldn't help regardless. Just don't trust anyone sketchy to begin with, and you are all set.
All excellent advice, thanks for taking the time to provide it.
Again, seems like maybe a grey area like the account trading, but who am I to judge? I'm just a Newbie for now.
Though, I have contributed pretty heavily to other knowledge spaces like Quora. I hope I can be as accretive here.