My answers just display as hiragana, how do I change that?
You need to log in, and on your profile page there's a dropdown that allows you to change between romaji, kana, kanji, and kanji with kana. Yes, I know it's a bit stupid that that's the only way you can change it, it will be brought out into the 'configure practice session' bit so that you can change it without logging in. Patience...

Please ask any questions you have here, and I'll endeavour to answer them (well, as long as they're relevant ), and add them to this list.