I don’t think you need to do the DVD-A authoring in Wavelab 6. According to the manual it’s still there in 9.5, and has been in all the intervening versions as well, afaik.
Yes, but simple and without any menu. WL9/9.5 has less features than WL6 regarding authoring. But I could install WL6 on WIN10 and it seems to work stable.
BTW: I did not find any working free/open source solution to author an additional DVD-V part that contains a mpeg2 video + 9624 Stereo wav file. AC3 is no problem, but hires wav is. So the disc could play on an DVD player if it contains DVD-V part. WL6 is capable to integrate this.