Hi Tiff
1. Feeding in the fridge: offer him food just b4 you do a waterchange every day, hubby used to leave a wee piece of food (cut up earthworm) in overnight after a waterchange and if it wasn't eaten in the morning remove it.
2.He may not eat anything, while in fridge, cos his metabolism has slowed down.
3. He will poss. poo again within the next few days, if he is still in fridge, as well as poss. puke up any undigested food, which is also normal, as we discovered! (tho I couldn't work out what it was at first until I asked on this site)
4. The mark on his tummy - is that the red mark that you mentioned in your other post? If so, his skin is still a little translucent, based on size you mentioned (ours were that small) so you can see part of his stomach. As he grows older/ bigger his sides will just become more solid/white looking. (Hope that doesn't confuse you!)
5. We fed ours at that age twice a day, a few little bits at a time till we worked out how much food they would eat and not regurgitate or leave uneaten.