...do you know which apply specifically to AT&T?
I assume you mean AT&T prepaid vs AT&T postpaid. I do not know the specifics. You'll just have to check their website or contact AT&T for details.
I believe the coverage should be the same.
Voice and data coverage areas may or may not be the same, depending on several factors. There's a pecking order, about like this:
Are you postpaid, a prepaid customer of the network you're using, a prepaid customer of a wholly-owned MVNO, like Cricket is to AT&T, or a prepaid customer of an independent MVNO like Straight Talk?
The farther down the pecking order your provider is, the more likely your coverage area may be reduced due to roaming agreements not applicable to your service or other restrictions placed on your service provider by the network operator. IOW, a MVNO often purchases the rights to use only part of a network to reduce costs, offer regional service, concentrate network buys in high population areas, stuff like that.
However as the post states, priority may be given to postpaid customers. I don't know to what extent this would be true (ie. how often would you get throttled down or dropped due to congestion)
Just to be clear, here we're talking about priority access for data service. Voice is not prioritized, other than coverage area restrictions, if any.
As for when or how much throttling is done, of course it varies by network conditions and the level of access you - through your service provider - are paying for. Network operators offer MVNOs contract packages of various access levels. Again, you should contact your service provider for more information. Lotsa luck with that.
I have google voice so conditional call forwarding is built in.
Conditional call forwarding is NOT part of Google Voice. Conditional call forwarding is provided by your carrier.
I assume all customer service I get will be "b team" so I suppose that doesnt really matter so much.
Unfortunately, a lotta companies don't seem to have an 'A Team' for customer support.