The more springtails you use the quicker the new cultures will take off. I use a few hundred, possibly a thousand including all the babies. They start producing new springtails fairly quickly. Start them with as many as possible. I was running low on the temperate springtails so I made a culture with only about 20 adults and about 2 months later there is quite a bit more.
I keep my springtails in gladware containers, 16 oz. up to 76oz. with peat moss on the bottom with some charcoal on the top. I keep the temperate closer to 70 degrees, and the tropical closer to 80 degrees. I dont think the temp matters too much, but you will notice a difference in production when seasons change and the room gets warmer or cooler.