Room temp is perfect. No extra heat needed. In my office tank - I did notice they became less active when the room got into the low 60s before they kicked the heaters on for the winter. Anywhere between upper 60s up to low 80s they will be fine. Lower, you may want to move the tank somewhere warmer.
I am asking $10 each, 4 for $30, 5 or more $7 each
They are young, and will need about 6-8 months to be full size and of breeding age. Color comes in young (at about 1/4 grown they have little red claws), and gets better with each molt if supplemented with carotenoids in food.
The biggest are about 9 mm carapace length. Smallest 3-4 mm carapace length.
This isn't the first time I have raised them from this size, and I can confidently say that with even the most basic of setups (moist long fiber sphagnum and some kind of cover - leaf litter, driftwood, etc) and food with enough calcium - they will do very well for you.