Well, since no one ever answered any of the questions I asked I guess I'll go ahead and answer them now in case someone finds this thread in the future and has a similar situation.
First off, yes they are gray tree frogs.
And yes, there is a huge amount of variation in how green the tadpoles get when they get all four legs. Some turn bright green right away, others stay completely gray.
Tail absorption varies quite a bit from frog to frog, but generally seems to take in the 3-4 day range. Once the fins of the tail disappear the frog is pretty much ready to come out of the water so if all that is left of the tail is the central line and the frog isn't making any attempt to get to land you may want to push him up to the edge of the water line so he gets some air and maybe gets the idea to get out. I lost one frog to drowning because he never made any attempt at all to get out of the water. After that I watched them more closely and "encouraged" any that didn't seem to be getting out on their own when the time came.
Sinking spirulina pellets sold at any pet store are perfect food for the tadpole stage and don't really foul the water much if they don't get eaten right away. Hydei fruit flies are perfect for the newly formed frogs and very easy to culture.
As for an alternative to crickets I decided to go with green banana roaches. They stay relatively small for a roach, have soft bodies, and don't look gross. Plus they won't make a ton of noise or smell horrible like crickets would and any escapees will die in a day or two since the local environment is not suitable for them. Seems like the perfect feeder to me. It'll be a while before I need them but I went ahead and ordered everything I need to set up a colony anyway so they'll be ready when the time comes.