Colleen - Congrats on your new froggies and mossball! They all look absolutley ADORABLE! Do they have names yet? Mossballs are awesome, and need very much of anything to thrive, so I'm sure it will do well for you.
You mentioned that you have 0 on nitrAtes, as well as the other two. This makes me a bit nervous, as it is usually indicative of a tank that hasn't been cycled yet. You'll want to pay very close attention over the next few weeks as your nitrogen cycle establishes, and do water changes as needed to keep ammonia and nitrIte levels down for the health of your frogs (For the health of your creatures, ammonia and nitrIte should be at 0, nitrAte should be under 20 or so). Unless you keep a small uncycled tank - I'm assuming Frank is a Betta? I don't *think* the betta can pick up any illnesses from the frogs, so you should be all right there, but the two species don't always play nice together, so be sure to watch closely until you're sure.
Your froggies DO look super chubby and healthily adorable!
SageMyster - They sell 'em in packs of little cubes in the freezer section of almost any fish store.
One full cube will be WAY too much food for only one frog. What I do is pop out a cube, use a knife to slice about a quarter of it off (or however much you need) then wrap the remainder of the cube and put it back into the freezer for next time.
Like Olympia said, you'll want to defrost it before you put it into the tank, because the water that it's packed in will only add waste to your water, and the frogs shouldn't eat them frozen, anyway. I defrost mine in a tea strainer - it doesn't take long!
I hope you get your poor little guy some food soon! He must be starving by now!
OLYMPIA!!! YOU GOT FROGGIES!!! HUZZAH!!! I don't think you're a bad person at all!!! You're gonna love
these little guys. . .and they'll prolly be easier to keep than those adorable Puffers, anyway! They're the cutest! Good call on getting two at once - QT is a PITA, and they're so much more fun in pairs, my two are adorable. (mine got dumped together for better or worse during the many days without power - crossing fingers that all goes well here!)