I have 1 African Clawed frog, a 4-year-old female. I used to have a male, but he got out through the ONLY hole in the hood, which is the space where the filter is. I ended up covering that with mesh.
Do watch for this, they are escape artists, and the ACFs will dry out quickly.
I've never owned the dwarf version, so I can't comment on them at all.
I do use a filter with my tank (she's in a 10 gallon) because the water gets dirty very quicly without, especially when feeding dry food. Using feeder fish cuts down on the mess considerably. The filter is quiet (it's a waterfall type) and I really don't think it bothers her considering she likes to bob up and down under the flow
I'd like to get another ACF so she's not alone, but it's hard to find fully grown ones and she'd just eat a little one.
has information on xenopus, but it's more from a research point of view than a pet ownership point of view. Nonetheless, there's useful tidbits about water conditions and such. I believe they use only well water at NASCO, but I just use tap water that's treated for chlorine/chloramine (very important) and has some other beneficial stuff in there. I believe it's called Stress Coat.
I'm not all that surprised that the sites you've visited have different information. There's more than one way to raise a critter, and everyone finds what works for them and thinks it's the best. I'd say water quality is supremely important, but other than that they seem pretty easy to rear. I had a BUNCH of them in my lab at one point when over spring break the temperature controls failed and temperature spike caused my tadpoles to metamorphose earlier than expected.
Another interesting note, if you get a male and female ACF they will "sing" to each other, but of course you'll have to be prepared for the possiblity of eggs.
Good Luck and let us know what you decide!