The best place to ask about adfs is in the invertebrate, amphibian etc section. There is a load of info on them in there.
Owww, that's too cold probably why the fell ill they need a tropical tank temperature, the same you have for the betta's, at least above 75 (usually do this in Celsius)
They do like groups (I'm still building my tank so I'm taking things slowly so it can adjust and I only have 2 atm)
Also don't forget to add water-treatment to the tap water to make it safe
2.5gal is the absolute lower limit for 2 frogs alone
If you want to add more frogs (or fish), you're definitely going to need a bigger tank, with a good fitting lid.
@lilfishie, didn't realise moss balls are hollow, might just get one then and cut it in half
You just saved me a couple of quid
Meant the girls have a 10 but if they get their own, they get a 2.5 gallon. Using Prime - is that okay?? I'll get a heater ASAP