I am a new owner, too, FBT's. I have the same questions you have about worms. I bought wax worms, came home, they were all dead, exchanged them. Tried crickets (which frogs love) but they are hard to catch and one ended up in my car. I bought earthworms from walmart but they're so big I have to cut them (yuck) and they don't move long after doing this. They also have a way of slipping right thru pebbles in land area. So, I got mealworms. Now these worms are just plain boring: they lay there until you poke them, then they suddenly move. They also die if in water a little too long. I've gone thru many while the frogs think about whether they want them or not. Our pet stores don't sell roaches (I have not found any) and they sell another type of worm but told me these were not what frogs want, forgot their name. So, I rotate between different worms and crickets.
About mealworms: some say frogs can't digest them because of their shell and to cut heads off first. And others say (like the store) to give them mealworms. So, now I'm thinking there must be something else I can offer. I wonder if they'd eat canned dog food if I could dangle it? But how would I dangle that, it would fall apart. Maybe plain cooked spagetti? it might look like a worm to them. Yep, maybe I'll try that. If that doesn't work, there's always Arby's (LOL). Wanted you to know someone else has the same questions you have.