Overall good buy, but I fail to see how you could have spent $250 on that (unless you're not including taxes). Usually that package would retail for ~$275 before taxes (unless you got the mag and battery tossed in as freebies or whatever).
Also definitely not a good idea to hook up to 300V.... It's likely going to explode in your face in a miraculous fashion, burn your house down, and kill all your loved ones.
This is one of the best kept secrets in batteries and stuff but buy this:
and some 7.4V lipo batteries and you're set. They're actually pretty good quality AND cheap as hell too (in fact I bought 4 batteries (~$30) and some other stuff for a little under $75 shipped to my door + ~$7 duties/taxes).
As for charge time, it depends on how much current you're trying to push to the battery. If you've got a 1000 mAh battery and pushing 100 mAh through it, it'll take 10 hours, if you've got a 1000 mAh battery and pushing 4 Amperes through it, it'll only take 15 minutes. Ideally charge at "1C" which in the case for a 1000 mAh battery is 1 Amp (basically charge at the same rate as the capacity of the battery and it will take ~1 hr). Now that said, I charge my batteries at 1.5-2C.