First off, hello & welcome!

Now for the advice :

You can use tap water as long as it is de-chlorinated. make sure the substrate is moist but not muddy.
Your temps sound good. UTH should always be used on the side of the frog's enclosure so they don't cook themselves by digging into the hot spot.
You're going to find that the red wigglers may not be to their taste. We breed and they will take them at first and snub them after the first one. I would suggest Night Crawlers instead. Also, the wigglers are tiny and even though you will have to cut the night crawler to appropriate sized pieces, you only have 2 frogs to feed so a 24 count will last a while in the fridge.

How big/small are these frogs? If they are still small, 10 gallon may be a bit large for them, i would suggest you cover 3 sides of the tanks to give them a sense of security. And yes, distilled water is bad for them. You can offer them food nightly but they may not eat every night depending on the size of the last meal & their size as well.

Plenty of folks here to help with more advice if you need it too!! Hope it helped!