Wow, what a hard situation to be in. First he is going probono so that feels weird because if it was me I would feel like I would owe something and it doesnt' sound like this was discussed too much, it is like he just decided to do it..
Then he asks for you to do something, that isn't therapy related for you. That would make me feel uncomfortable for sure.

I wouldn't do it because it already feels uncomfortable on many levels. If you did you would have to worry if he was happy with the work, if he says he was happy with the work, you would have to wonder if he is just being nice because you are a client. Nope, T's should avoid dual relationships when they can for many reasons.