I have the A6500 and the Fantasea housing, I have been pleased with it. I did not buy the 16-50mm kit lens, although I have friends who use this with wet lenses for good results. I have the 10-18mm and the 50mm macro (to be honest, I don't use the macro often). My only negative comments are as follows:
50mm macro - this lens really hunts for focus, to the point where manual focus is sometimes a better option, I wish I had purchased the 90mm and still might, although seriously considering an upgrade soon.
10-18mm - I get terrible issues with the white printing on the lens and to a certain extent the actual lens reflecting in the dome port and it turns up in your photos to be removed in post, sometimes its very time consuming and almost impossible to remove.
Outside of these, you should be able to get some great results with the setup...