Welcome to the forum Elliot. Is this what you're talking about?
http://www.frogforum.net/avatars/tom...ine=1256350595
(That's Tom Highum's avatar)
If so, then they tend to be rather shy eaters but they should be eating within a day or so of you acquiring them. I would first try to make sure they are eating before I threw a bunch of roaches into the tank with them, though if you're using Blaptica dubia roaches then there's no harm in it. I would feed them every 3 or 4 days initially, and see if you can find uneaten roaches each time. I would underfeed rather than overfeed - 1-2 roaches per frog until you are sure they are either eating them or not, then raise or lower the number accordingly.
If we are talking about Megophrys, then they don't make much use of a tall terrarium, but they do like humidity. When keeping frogs there is almost no such thing as a tank that's too big.
I use leaf litter in frog and salamander tanks, often with a coconut fibre substrate, so that should be fine. Make sure the leaf litter is from a pesticide-free and herbicide-free area. I usually dry leaf litter completely for a few weeks before using it, provided it's pretty dry to begin with. For leaf litter I receive from others (I get "Live Oak" leaves from Florida, I boil water on a stove, throw a bag of leaves in and then stir it around for about 30 seconds, then I pour off the water and put them on a baking tray which I then place in pre-heated oven at about 300 degrees Fahrenheit (about 150 Celsius) in order to dry the out again (if there are many leaves on the tray I often have to shuffle the leaves around several times in order to dry them all).
I've heard of people using the microwave to treat leaves and I've not heard of anyone having problems doing so. I've never done it because microwaves aren't great for sterilisation.