Yeah....

first of all welcome to the forums!

Now for your questions and I'm going to disagree with some people here

Yes, if you bought them from petco - most likely they are WC, and the guy from the small store giving you "the look" is very understandable because of the reputation petco has. They are not competition and never will be, nobody would buy any animal from the petco knowing their animal housing and selling practices. Small, specialized stores on the contrarary, care about the animals and their wellbeing and will be definately better source of information and animals too.
I am generalizing here, there are small stores that you better run away and I know nothing about the pet store you have been to. And in any way I'm not blaming you for getting frogs at petco, you care and the fact that you are asking questions shows it! and I very strongly susspect you saved them too.
CB whites are not that common in pet stores in North America, they are appearing from time to time, but still majority on the market WC and unfortunately most of the imports are from Indonesia, where about 20% of whites population are infected with "spargana" ( intermittent form of tapeworm). The is nothing you can do about it without possibly killing the frog, it's not danger to you or any other frog you have, in a year or two you might start to see ulcer looking lesions. And you might not see that, so don't stress out now.
The other parasites are different, but easily treated with panacur. You can contact dr. Frye ( Milan vet. Hospital), he can ship meds to you and explain how to treat.
And yes you don't want to mix WC and CB. After deworming and long time captive care ( at least a year) in theory it should be fine, but personally I would never do it. CB are not being exposed to the stuff WC did, there is always a danger for CB to be in a contact with WC.


Heating - yes infrared lamp or ceramic heaters are better then heat pad, safer too heat pads don't heat up air well. Get the dome with the dimmer so you can control the temps. Or you can get controller, hydrotherm is my personal favourite.
You might want to get a thermometer ( digital) to check on themps.

wild caught food. You DO NOT want to do that! As Jason pointed out they will carry everything and anything that we damp into the nature (Pesticides, chemicals), that stuff travel far and unless you are 100% sure the area ( big area) is free from roads, agriculture, etc you better not do it. I'm not sure though that kind of area exists, unless may be in the mountains after like 2-3h hike
i very highly doubt you want to culture crickets, like really... They stink like no tomorrow, you can minimize that by cleaning, etc, I did, thank you much, I'd rather go buy, and I buy 1000 Crickets every 2 weeks. For 2 frogs, you don't need much, just get some from the pet store, gut load them, keep in a separate container ( tub) until all eaten, then clean the tub and get more.
And if you having 2 frogs and cricket breeding going.... What are you going to do with all the crickets? They produce a lot and there will be escapees too

you our might want to check tree frog subforum, lots of information on whites here as well it would be better to ask in there too, more people will see it.