Ditch the sash.

In terms of the sporran, a day sporran or semi-dress probably works best. That said I have worn my kilt to 3 weddings, 2 at the express request of the bride (the other was my own), at all three I wore a dress sporran - although with different jackets (PC, black argyle and charcoal crail). However, my dress sporran is fairly subtle in grey seal, with a relatively plain cantle - and whilst not entirely correct for daywear, I think I can get away with it (esp. as many others wouldn't appreciate the difference anyway). Go with what you think works best or are happiest with - but maybe best to keep it low key.

In terms of the hose, I would avoid white, cream or ecru - unless you are in a pipe band or wearing a hire outfit. Black is probably a better option and would work well with your tartan and choice of jacket. Otherwise, a plain colour picking out either the main field or one of the secondary colours of your kilt could be an option. Claret would probably work well with your tartan.