Hey guys, new member...

[Majinite]

Hey guys. I've always been interested in frogs, kept plenty as a kid and now I have a son of my own who is interested in them. I always liked the look of the Australian Whites, so I picked up a couple at a local pet store here. Unfortunately, to my knowledge, no local breeders in this area of WA state. I did have a few questions I was hoping someone could help me with:

1. Both my son's tree frogs are from Petco. I was told by a local pet store owner that all Petco frogs are wild-caught and will have parasites. Does that mean if I buy a captive-bred tree frog, they can't co-habitate?
2. Is there a surefire way to tell the sexes apart? I read online to look for nuptial pads on a male frogs thumb. Are these easily visible or only during mating season? I also read that males ears are larger than their eyes, and female ears are smaller. The two I picked up for my son seem to have smaller ears, so I'm assuming for now they are female. I also haven't heard them croak at all, I did play a couple White tree frog calls on Youtube just to see if they'd react, but nothing so far
3. Assuming the two tree frogs were wild caught, is there any danger in feeding them local critters? We have lots of bugs around here, I've only been feeding them petstore crickets for now. It'd be nice to just grab a few earthworms and throw those in instead of paying for bugs.
4. Is there anyway specifically to breed crickets in captivity? Again relating to question 3, if I do have to purchase commercial crickets, it'd be nice to have my own at home as well to augment that.

Any help would be greatly appreciated. When I get home, I'll try and take some close-up pics of the frogs, I'm sure that would help with the male/female debate.