I removed my tank last summer. Here is what I did. Like you, I took off the sending unit wire and all the bolts. I used a siphon pump to remove all the fuel I could (nearly 100% of it) and I used dishwash detergent (soap?) to lube the rubber grommet. It came right out!
My tank was coated with flash rust so I took it over to a radiator shop and they "renewed" it. It's more expensive than a new aftermarket tank but it's supposed to last forever. The shop had also sandblasted the exterior so I painted it with two coats primer and two coats of "hammered" silver. I painted the neck with 4 coats of gloss black.
I taped off the end of the filler neck (very end) and the place where the sending unit locks into so that I could be sure to get a smooth seal with the new grommet. I bought a new sending unit but I haven't put it back in yet.
Before removing the tank (didn't realize what trouble I had) I unhooked all rubber (and removed it) from the entire fuel line.
I now plan to make all new fuel line myself from Poly Armour, NAPA carries that. I bought my own flaring kit, bender, and tube cutter.
The renew process is about $250.00 BUT it guarantees you better results than an aftermarket tank, according to VWNate on here. I liked his arguments and I decided to go that route over the aftermarket tank route I had originally planned on. GOOD LUCK.
