Some really good tips here.
My 2.2m dome fitted on a flat-bed trailer in two halves, with the dome section complete; I split it at home to clean it up. Getting the silicone off was the biggest job for me. Three different softeners had no effect - I even tried leaving it overnight but still wouldnt budge. In the end I sharpened a stiff scraper on my grinder wheel and used this as a blade (wearing heavy duty gloves).
As to polishing, my dome had sat underneath trees, in a farmyard for years before I purchased it and was covered in algae and black-spots. After jet washing, soft-sponging and washing down the surface was gleaming. I figured if it was this good looking after years of abuse, polishing may only enhance it for a while. The glossy finish has not faded since I installed it 6 months ago and this is enough for me without annual maintenance, besides which I have the dome mounted on a 600mm high table to get me views over the surrounding buildings and reaching the top would be tricky at best.
I did replace all the bolts with stainless domeheaded hex bolts and stainless nuts/washers, while Screwfix had a special price on - a few pounds well spent as I see them every time I am in the obs. I need to replace the bearings in the dome rollers as they had been left exposed to the elements for years at the farm.
I also replaced the nylon studs to the apeture, with bearing rollers of the type use in shower enclosure doors. A little Blue-Peter work needed here but it now glides like a dream and could easily be powered by a motor if I felt so inclined to build one (my dome is the older model that cannot be retrofitted with the Pulsar automator system).