I wore no 1s at my last place, spent many hours seaching publications for the DS solution but got no-where. Corps Instructions had alot on Offrs but not ORs. I ended up asking the corps ASM at the time what the score was.
You can wear a plastic white belt with the REME buckle (Â£20 ish for the Corps shop) or a plastic belt with brass buckles (from 37 pattern belt). if you can ponce once you can wear a buff belt with the "Dieu et mon Droit" brass clasp.
If you're a tiffy or JNCO you can wear a No1 pattern hammer & tongs, just scoc hammer pincer badge and it will come up.
SNCOs can carry swagger sticks/ drill canes. REME sticks are finished in rose wood. Pace stick if you are a drill instructor or hard core walt.
Not sure about red sashes, only seen them on SSgt RDs & CSMs. Certainly not below Sgt.
Drill boots for effect but chelsea / george boots for comfort. I wore issued shoes (waxed and bobbed of course) when in the mess.
But if you are wearing them to get married wear what ever you want, aiguillettes look camp but the best one to wear is the Household Cav LCpl one. But a feather boa would look better.