So far I only have the temparate variety of springtails...seems to be hit or miss getting them to culture in a viv, which I attribute mainly to most of my tanks being high 70's and low 80's.
The tank I had the most luck with is a vert ten for imitator, the substrate is 1-2 inches leca, 2-3 inches of ABG mix from T+C terrariums, and 1 inch of spagnum on top. It is lit by a 18w cf twist bulb, a couple of inches from the top, so it doesn't get much warmer than room temp at the substrate. At any given time, you can see springtails in the moss, on the glass, and on the background. I don't feed the springtails anything, though you can, and if you do they will concentrate around the food, which will make them easier to find.
I hope when I get some of the tropical variety of springtails, that I can get all of my tanks to support springtails.
As far as how many, it's just like starting a new culture, put as many as you can spare, the more you put in, the faster they will populate. This is especially true if there are already frogs in there...you need to have some survive to continue the population.
I'm just starting to play with isopods and woodlice (are they one and the same?). The ones I bought from Flyculture seem really slow to get going, as I ordered them in november, and just now am I starting to see babies.
From what I've noticed they seem to like coir mat, I don't know if it's because it stays a little drier, or they like the spaces inbetween, or what, but that's what they seem to like.
I was tearing apart a tank a month or two ago, and I had some woodlice in there that I never even knew about...must've hitched a ride on some wood I put in there...and they were everywhere there wasn't light. I might try to get a pic of them and see if someone can I'd them. They seemed to really like dead bromeliad leaves. I'm going to try and seed these in most of my tanks, as it was obvious they liked the viv conditions, and they did no harm to the imi's in there.