Hi Gareth.
I just use a MIG but have experimented a lot to get the right settings. You need to use a higher power setting than you would expect so that you get good penetration and a weld that is relatively flat, too low power and the weld just sits on top, looks hideous and you need to do a lot of grinding....but this means you can blow through the weld very easily unless there is very little to no gap in the butt join, wire feed needs to be backed off too so you aren't supplying too much filler. Its all a balancing act and requires a lot of trial fitting to get the gaps to a minimum on the butt join before welding....... and you need to manage the heat and warping.
Yep, shifter is rubber bonded. You can buy a bizillion different aftermarket shifters for BMW's for exactly that reason. Ive got the lever out of the Z3 which is the shortest throw factory setup, I will leave this standard for now and once its driving will make a call on which way to go but suggest I will probably do the same as yours. How did you "de-bond" yours without destroying it?
David