Like everyone else pointed out, and as you already found out, the program isn't as great as other airlines. Yes you can sign kids up on your email via telephone, but it costs $19 per point to transfer points, so it's usually more expensive to transfer a few points than it is to just buy a ticket. And yes they expire after a year - you can pay to extend them, but again, not cost effective.
I always seem to get just to the 8 points I need, and then have nothing planned & lose them. I had 4 points expiring Feb. 15th so I cashed them in for a busines class upgrade voucher last week. Now I have 1 year to use the voucher - so keep that in mind, you can cash out your points for a reward close to when they expire, and then you have 1 year from that point to use the reward. I don't know if this works for flights - not sure they award "vouchers" for flights or not.
I've found the best way to accumulate points is with their gift certificate sale, which I think is the beginning of January. For about 2 weeks you get 1 A+ reward for each $100 in Airtran gift certs you buy. Since we usually travel in March, I'm ready to book at that point & buy however many $100 gift cards that I need to pay for the flights. Then I turn around & use them to book right away.
I just booked flights on AT today with no promos or codes, it killed me! About a month ago I got fares of $62 each way ($145 total RT) for my 1st trip in March (12-16) so it was hard to hit "purchase now" for 3 tickets at $200 each for March 22-28. But I've been watching the dates like a hawk for weeks & they've only increased. Last year at this time they were up & down frequently, and I took the risk of waiting to book 2 weeks out & it paid off. Since I didn't see any price fluctuation in the last 4 weeks I just bit the bullet & bought them. Now I'll play the watching game to see if they go down, so I can call & get a credit towards another flight, or towards seat assignments.
Tracking airfare can be a full time job!