The non pro version is AC/DC also. The pro version is slightly different power on DC but it looks like the main difference is just the fact its a Dual Charger.
Sounds like instead of converting a Server PSU you want to convert a PC PSU so you can create 5V and 3.3V terminals as well as 12V...
Yeah a lot of us in here can help you figure out how to charge thats np. You do want to get a good charger though so you arent potentially wasting money on something thats junk or youll outgrow in 12 months. Two of the better ones I can think of are the HOTA H6 that I linked before and the Hitec...
Hobbyking.com is a good place to look for lipos. They have search parameters that include sizes. Buy the highest mAh 2S LiPo that will fit your batt tray.
While you're there Id pick up a good AC LiPo Charger too. At least a few folks here would recommend THIS charger