Welcome to BP.net :)
1) False. They will grow to their adult size regardless of if they are in a 10 gallon tank or a 100 gallon tank.
3) I would imagine so, if they have no rough/sharp edges, and you clean them before you put them in the enclosure.
5) I wouldn't put her in a 100 gallon yet. That could stress her out a lot. They like snug areas more :)
6) Infrared heating bulbs have a higher wattage than the red lights at walmart, I believe, since they are designed specifically to put out heat. :]
Shellie