Please Help! I kill house plants!

Please Help! I kill house plants!

I was going to buy a bouquet of flowers for Thanksgiving but to get what I wanted would have been almost 15 dollars. Sitting there next to the cut flowers was a little pot housing 3 Kalanchoe plants, one with red flowers, one with yellow, and one with orange. This was 9 dollars. The cheapskate in me won out. It lives in my kitchen, so it gets decent morning light from the East facing kitchen window, decent evening light from the West facing living room window and resides under a florecent light in the evenings. I've been sticking my finger down in it's dirt every few days and if it feels dry I give it an ice cube (tip from a florest friend.) Yesterday i pinched off the remaining flowers, so its bare but the foliage is pretty. Here are my questions, 1 - do these 3 plants need a bigger pot? They're still in the little plastic one that I bought them in. 2 - should I keep them in the same pot or give them each their own little pot? 3 - what kind of dirt should I get for re-potting? Will any kind of potting soil work? 4 - how dry is "moderatly dry"? The instructions on it's little tag said that it needs moderate room temps (65-70) and moderatly dry soil. 5 - Right now we're probably a little on the low end of the recomended temps, durring the day our thermostat is at 55, when we're home it's 68. Come summer time though, it'll be MUCH warmer than that (85 durring the day and 78 in the evening) Am I going to kill this thing because of varying temps? I do a very good job of killing house plants. I've yet to actualy keep them alive, mostly they're in my husbands care until I can get them outside into the dirt. Currently this plant(s) seems quite happy on my kitchen table and I'd like to keep it that way if at all possible. Any hints or tips would be gladly excepted.
Pollinating ID

Pollinating ID

My very red bedroom

My very red bedroom

Stupid Gardener Tricks

Stupid Gardener Tricks

Welcome to Our Home!

Welcome to Our Home!

Aerogardening in the cold of winter

Aerogardening in the cold of winter

Mandevilla Disease

Mandevilla Disease