Yeah, your setup looks like a great start. I was glad to hear that your setting up a UVA/UVB. I'd still encourage you to release it, you can always buy a captive bred one :) Anyway, I'm absolutely sure its a three-tripe mud. Look up pics online, musks faces are shapped differently and the never have the lines down the shell like that. I have a three stipe of my own, so I'm positive. They do make really good pets, and don't get any bigger than a stinkpot... the only really difference in their care is that they like shallower water. I don't know how long it takes to close their shell, I've never heard of a baby not being able to do it, although mine doesn't close the whole way, you can always see a little turtle sticking out the front and back.