3Q's: Stuck lugs & Jack/Heater Safety

These are pretty newbie-ish questions, forgive me.

Problem:
1) The previous owner over-torqued the lug nuts. When I had my front two tires changed over to all seasons during my NY Safety Inspection the mechanic who took the rims off said they'd been torqued to almost twice spec. Maybe you're thinking, "But wouldn't that snap the bolts straight off the hub and make your wheel go bye-bye on the freeway?" Yes, that (almost) happened. But only to one rim. So, the mechanic got the front two wheels off, the car decided to loosen/break another on it's own, and now I'm left with the last rim. I figured I'd be able to get it off on my own, but I was wrong, and at this point the car is in pieces. I've tried wd40, a huge mallet, and not being a pussy. Any suggestions?

Safety:
1) I started working on my car again since it's warmer out (and spring break). The thermometor in my garage says 35 degrees and being from California I think I work best at say, 70 degrees. I'd like to have a space heater inside the garage but I'm concerned that I'll blow up the car/myself with fuel vapors, etc. Is this safe?

2) I went to Napa to pick up an extra pair of jack stands, but they were having a sale and out of all sizes except "6 ton" :). I figured wtf, they're cheap. The problem is that they're taller than my 2 tons stands, I'd guess about a foot and a half tall.
a) Is there such a thing as jacking a car up too high?
b) I brought the 2 ton jacks up to the same height, but they have a tiny bottom stance in comparison to their new height. Any worries that they'll tip over?

Thanks for any replies :)

to get the rim off, get the right sized socket...and a rachet. make sure both are 1/2in. drive....now get a breaker bar and put it on the end of the ratchet handle. this provides more torque to break those suckers loose....as for the heater get a torpedo heater. they throw out the heat fast and are safe to work around...as for the jacks, just make sure you put the jacks under the jack points on the car...if you have a manual, it'll show you where to place them. don't jack it up way too high, though...you don't wanna make your car vertical, heh...

if the breakerbar doesnt work try adding a little heat with a propane torch. little being the operative word if u see it turning orange uve gone to far

I tried the socket/wratchet/breaker bar idea with no luck. Looking around online it seemed the next thing to do was get an impact wrench, nascar style, which I got off e-bay for cheap. 120v, and 240lbs of torque (forward and reverse). Okay, not quite nascar style, but 240 still sounds like a lot to me.

I'll grind the mofo's off if this doesn't work. If that doesn't work I think I'll try tightening them until the bolts snap off :)

Thanks for the help, first off. I finally got the lugs off the one rim.

I decided to take a trip to find a Home Depot solution when the half inch drive and breaker bar wasn't cutting it. I measured the wratchet and my garage and ended up getting a piece of five foot copper pipe to act as my custom breaker bar. I put the pipe at a 15 degree angle to the ground and leaned my weight on it until they budged. I was scared they'd pop off all of a sudden and I'd plant my face in the ground, but they eased off real nice. The lubricant probably helped. Yay.

I looked into the torpedo heaters which are kinda pricey. I'll pick one up when I get the money together.

The car is on jacks now, ridiculously high off the ground. Cool, I guess. No complaining about installing exhaust or otherwise working under the car.

nice