Unless you use a voucher then it would be only 4+ credits (one voucher) for both legs.
Correct, if you are upgrading using A+ credits then it is 4 credit total for both legs. Paying the fee it is two fees for two legs.
That would be awesome if I could check in before the 24 hour mark. Flight takes off at 8:00 on a Saturday. At 8:00 on Friday, I had hoped to be on my way to the Magic Kingdome for the Morning Celebration. I will definitely try to check in earlier.
I may also have to try upgrading for the first leg on the way down. If I can do that AND they will waive the baggage fees, my "fuzzy" math tells me it would only cost an extra $9. My flight down takes off at 5:50 a.m. and I would love to catch a nap between the Quad Cities and Atlanta.
YOu can't really checkin more in advance of 24 hours, just upgrade to business class paying the fee. I don't think they actually check you in though. I don't have experience with this. You would have to check out this thread at FlyerTalk. http://www.flyertalk.com/forum/airtran-airways-rewards/955615-upgrading-business-class-exact-time-reference.html