Seb, to keep your drysuit zips in tip top condition you should grease/lubricate them. Ravenspring sell packs of suitable stuff. We also Vaseline the studs on our Gecko helmets.
Regarding scrubbing with soap, have a read of the care label/tag or contact the manufacturer. We bung our waterproofs in the washing machine with half a soap powder tablet and they seem to be OK, but I wouldn't like to promise that all fabrics would be OK!
And don't forget to check your lifejacket regularly, e.g. gas cylinder is properly screwed in, within date and nothing is punctured.