I'm currently running the Motul gear 300 75w90 fluid. It's a tad stiff in the middle of winter. But after a few minutes of engine and transmission warm up time it's fine.I ended up buying Motul Gear 300 oil. Is that good? Read good things about it. Also, what is “rear main seal to the billet iAbed”? Im going to have a shop do it for me. One is charging 400$ another 600$. No brainer going for the 400$ install
I've also got the iAbed RMS installed. Great quality piece that does the job of keeping oil where it belongs

As for the price of the install $600 is about average. I would rather spend a bit more for a VW expert vs a gas station garage that handles everything. If the cheaper one is a well reviewed VW shop then you should be good.