Nice man!! Glad I was able to throw you some advice that helped you out. Recalibrating the ESC is a thing to do, and usually the first thing I try when my remote isn't acting right, or certain functions have stopped working. My son once turned my steering trim all the way to the right and I didn't realize it. I'll leave the rest to your imagination. Results were a bruised ankle and a pissed off wife lol.
Yeah definitely get a LiPo as that's going to increase your run time significantly. That being said, you might want to make sure you turn on the LiPo cut off on the ESC so you don't kill your battery.
As far as LiPo's go, I personally like Venom batteries as they come with a universal connector, and a nice warranty. However, you'll pay a nice penny for them. My 5000mah 20c battery cost me 50$. Lasts about an hour in the Ruckus, and about 3 hours in my crawler.
If you're looking for a budget LiPo, best that I can recommend would be Duratrax
http://www3.towerhobbies.com/cgi-bi...&V=DTX&D=Duratrax-Batteries---LiPo---R/C-Cars
They have lower mah ratings for decent prices, but if you're looking for run time, if you can, plunk down the 40$ for a 4000mah 25c battery. Do you have a LiPo charger already? If you need a charger too, then might want to half that mah rating and grab a charger too. Nice thing with Tower Hobbies too, is you can typically find what you need covered by Easy Pay, where they break up your purchase in to 2 or 3 payments, no interest.