Apologies for the rather delayed response. I've been pretty busy offline.
1) If by "higher" you mean one that gives you more features like disabling of ads, etc., then no, there isn't. Staff membership gives access into the staff areas and reports in addition to mod tools, though, but said membership is only given through invitation. Furthermore, as far as public forum posts go, it's basically no different from "regular" premium membership.
2) I've had a similar issue before even though I don't use Tapatalk. I'm not sure what caused it, but I'm guessing the "Wait 3 seconds" notification is because the message is posted and then the software tries to post it again within an extremely short time interval. I could be wrong, though. I'd ask
@Brent W to take a look at this, since he's the tech guy.
Happy New Year!