16-55 is mainly for pros who need WR and use tripods for stability. It is noticeably bigger, heavier, and no OIS. It's also more $. It is not that much better if u get a still shot but the cons outweigh the pros.
You will do much better with the 18-55 and primes. 18-55 will be more usable on the small grip xt10. And F1.2-1.4 primes will give you the true bokeh that you need. OIS will help you get sharper shots without tripods.
A grip enlarger/extender will help on the XT10 regardless of which zoom u get.