For removing the plastic, it's held on by this rubber cement type of stuff, just grab hold of it and slowly pull, it'll come off. There should be some tach left in it so you should be able to put it back on. You can buy that stuff that holds it on at a hardware store, it might just be black silicon.
I'd go with the coilover's if you're going to need to lower and raise it now and then.
http://cgi.ebay.com/ebaymotors/ws/eB...tem=1871815054
This is the correct way to do it, where you have the coil over built into the shocks, they will offer the best perofmance and feal, but you're going to pay extra. Or you can just buy the ones like the Massives that you posted, they'll work too.