EZ On seems to be a pretty good name as far as tops go. Personally, if the rear curtain is falling apart, the top probably isn't that far behind. You have to take apart most of the top anyway, I would just replace both. Both usually run ~$300. If you are doing it yourself that's great, but if you're having it done go by what the installer likes. I know of a really good how to video.
As for the tank, I am ashamed to admit I just cleaned mine for the first time last month. Take it off to clean it, it isn't hard. Use hot hot hot water and good dish soap. This worked for me.
'94 Laser red 'vert. Still a 5-oh... for now