Lol, easy mistake to make....and I think I followed suit! Should have read cm!

Well I would say the humidity is good, and the temps are similar- I keep my whites around 74-76, though speak to some and they will quote high 70's -80 for the hot spot, with a drop into high 60's at night. As for the Tomato, he is at a high of 74, but the cool end is nearer 68.

As for the size, if you take with a pinch what others say, 1 frog = 10 gallon's- your tank comes in around 30 gallons. Now i'd say this rule would apply to a decent sized adult whites, they will grow the largest out of your species. I would at the least seperate the Tomato Frog, he comes from Madagascar, as oppose to Australia/ New Guinea for the Whites, and the Americas/Canada for your Grey's/Common. The secretions in each species skins will be significally different as to cause considerable stress.

If your frogs are all small still, then you could utilise some very basic tubs/faunariums to keep costs low for now in order to seperate. Or maybe speaking to the guy you purchased them off and try and exchange them so you have just the one species