[suicideneil]

There are limits to how many amps a motor can pull, but generally it should be fewer than the battery can supply, and the esc can handle, otherwise thats when things start to cook as you discovered. If you use the most efficient motors like Neus, and a 6s setup, you should get plenty of power yet run at a safe temperature. THe MM motors arent all that efficient -they seem to be similar to feigaos in design and construction- , so that would be why they run so hot, and suck the life out of whatever battery you hookup; they can pull a rather large current for their size, and thats down to the insanely high Kv ratings. The MM esc just gets stuck in the middle, and suffers from the high current being pulled through it.

If you switched the MM motor in your rusty to an S can feigao, or VXL even, you should see much improved temps and run times- use BrianG's calculator to determine your best voltage/motor selection choices; the same rules apply governing gearing/voltage/motor kv as has been previously mentioned.

As for batteries, much depends on your budget, but buy the best you can afford for the specific application (size, weight, capacity); an efficient system wont draw so many amps, so you can get away with a lesser capacity or C rating, but you want atleast 80amps on tap for any setup I believe (4000mah 20c, or 8000mah 10c etc etc)