Does this block them from even attempting to register, or does the block happen after they actually register?

As it states in the first post:

If the new registering member is determined to be a bot or spammer, they will receive a message telling them they are not allowed to register.

Yeah, that doesn't answer my question, which is why I asked it. WHEN are they notified?

The way I read it, is if they enter their info, and press submit, it is checked at that point, it don't block them from the site or from trying to register.

1. They hit submit.
2. Their information is checked against our servers and returned with response.
3. They are blocked if determined to be a spammer depending on what settings you have enabled. ( email, ip, proxy...etc. ).

When you ban by country can they even see the forum or does it be blank for them

The banned by country will block users from registering to the forum, it will not block them from viewing.

No way from making it so they don't see the forum
Maybe the next update

Which specific setting blocks disposable emails? That's the one I'm most interested in.

Its included in Top Spamming Domains.