It sounds like you are making great progress bonding with Dobby! As for the scratches, I always try to wear long sleeves, that helps some.
For bathroom time, make sure the toilet lid is down, and know that if he sees a hole anywhere, he might crawl into it. Make sure there are no exposed outlets, and no soap or cosmetic spills that he could walk through. Anything they get on their feet they will lick off and you don't want him ingesting soap. To keep them from escaping under the door I use a swimming pool noodle cut in half lengthwise, or you could use a towel.
They do like to explore, and jump from the towel rack to the shower curtain, etc. If you could make bridges with braided fleece he might like that.
I know there are a lot of hard surfaces in bathrooms, but it doesn't seem to bother them if they land on the floor or in the tub. I guess in the wild they are used to slamming into trees when they glide!