Knackered rusty shocks

[BlueTwin]

Newbie alert. I just picked up my first grey import bike (CB400 SF F2V, according to the sticker under the seat) which was ridden through a salty winter then left in a shed for 3 years. It has twin rear Showas which are pretty rusty but don't seem to suffer functionally. Could I pick your brains with some newb coilover questions...
1. Do you REALLY have to remove the entire exhaust to get the RH shock off (the bolt won't clear the end can and it's a one piece 4:1) ?
2. Anyone taken these Showa piggyback things apart successfully and not lost one (or more) eyes / limbs ?
3. Once the springs are off, would it be ok to shift the rust using electrolysis or should I just get busy with the emery cloth ?
4. Any recommendations on what to paint them with afterwards? Plastikote ?
5. Just in case I am unsuccessful in all of this, and simultaneously trip over a suitcase full of cash in the street, what shocks do you rate as a cost effective replacement ?
Thanks all, sorry for the dumb question overload.

[nampus]

Put the bike on the center stand, then undo the topbolts first on both shocks, you can then lower the swingarm and then the bottom mounts should be accesible without removing the exhaust. This is how I did mine a couple of years ago.
I then took the things apart (I used a springcompressor) and removed all the rust, had the springs repainted black, and cleaned the rest of the shock, after the new paint on the springs they looked like new.
The local car repair man sprayed them, I wasn't in a hurry, so when he had to spray a black car, he took the springs and did them too. For free

[BlueTwin]

cheers nampus, have just got the necessary bits for my abba stands so can lift it up on the swingarm pivot bolts now and get full movement of the swingarm.