Rather-B-Huntin

OK, just so it's known up front, I'm new to electric RC (so forgive my stupid questions).

I have a new Micro-T and the Losi Lipo w/charger. The Losi Lipo I have is rated at 180 mAh.

If I get another Lipo, with let's say, 250 mAh, can I use the same charger, or will I have to get a hotter charger for the hotter battery?? I gotta have something to extend my run times!! It runs great with the Lipo I have now, but for only 10 min. tops.

I've read other forum posts from guys stating they get up to 25 min. of run time with their Lipo.
Which Lipo should I get to give me more run time?????

Also, how long between runs should I let my engine cool?? I've noticed that after 10 min. with the Lipo I have now that the motor gets pretty warm. Can I switch to a brushless and solve this problem? If so, which one do you recommend and where's the best place to get one??

Basically, I wanna know what the best set up is to get the longest run time outta my Micro-T (and Mini-T too for that matter).