Here's my opinion/answer to question 2. I chose the butt joining method for the TK limbs because it is screen accurate. It looks better to me too.
You have to ask yourself what your ultimate goal is with your TK armor project. Do you want to be in the 501st? If so, then the overlap method is perfectly fine. I did the overlap method with my first FX kit (however that kit was built without my knowledge of whitearmor.net). BUT if you want to be in the 501st AND take your armor to the next level by also being accepted into the levels of EIB and Centurion status here on the FISD then butt joining is what you need to do.