Obviously I'm not well-versed on copyright infringement but I'd assume that unless you were using it for profit, you should be alright. Oliver Steeples from the Antweight community has had a full replica R2-D2 for years that he made, and rather than being hit for copyright claims, he was employed by Star Wars to make and (presumably) operate R2 in the new movie

BB-8 is a great droid and has been the subject of much debate on the Internet as to how it all works. I don't have any answers to the questions you posed, but I'm looking forward to seeing this project progress. Good luck with it!