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.
HTH