It's been 4 months since I changed the rotors, i'm pretty sure the pads are bedded into the rotors (or vice versa) as i've done enough hard braking since then. Grease is some German stuff, forget what it's called but comes in some yellow bottle and I put it on the edges where the pad slides into the caliper carrier slot slot and a little bit on the back of the pads like i've always done with every brake job I ever did
For what it's worth.. this article says to never use new pads on old rotors... (I know it says visa versa but they only go on to explain why it's a bad idea to reuse new pads on old rotors)
https://www.blauparts.com/vw/vw_brake_parts/vw_brake_pads/vw_brake_pads_set.shtml
and also, I have no idea where you are getting this VW parts must be superior to Japanese or Korean... last time I checked, my golf was made in mexico, for the Canadian market, where there is no autobahn. I also didn't get an electronic hand brake like the the rest of world does, and my OEM pads which are made by TRW i'm pretty sure are ceramic or semi metallic pads are not racing pads.
https://www.autoanything.com/brakes/the-best-brake-pads-ceramic-or-metallic.aspx
I've driven over 200km/h on the autobahn in a volvo wagon which isn't a german car and wasn't made for the autobahn... the regular pads performed just fine