What sand paper grit shall I use??

2-pack is called that because it's not supplied in one pot like (say) oil paints and whatnot. It's supplied in two - one is the 'hardener', which you add to the main paint and the two react together to make a much harder (they say) paint than a 'normal' one. Also called '2k' paint. It's very nasty stuff - highly poisonous - and your average facemask isn't enough, but the result is supposed to be a lot tougher. If you want something easier to learn first off, an enamel paint is supposed to be pretty tough (these Series didn't get 2k the first time around after all!), a bit more forgiving for the novice, and you don't need expensive breathing apparatus. It's what I'll be using anyway.

As you'll have probably realised from the commentary here and on your other thread, a good paint job is all about taking the time to do it properly. Don't skimp on the preparation, do all the steps. If you can, dismantle the panels - that's the ideal, plus you'll find it easier to do the actual work then anyway. And you don't ruin it if you have to take a panel off later, AND you find all the little rust pockets etc and can sort them now. New fixings (bolts and nuts etc), clean everything, follow all the instructions, and test your paints if you can first. If you look for Ash's 90 project on here, he's just been through the experience of having to redo his chassis paint from scratch because it all went on great but then reacted and peeled off.

[Or do an OK job half sand it and roller it on and go have fun - they're not showroom vehicles anyway right so what's a bit of peeled paint! ]