Shower Waterproofing

#1 - Bonding Kerdi membrane to drywall

I used GoBoard in my shower and came up a little bit short. Inventory was very low and I bought everything available. So I used a piece of 1/2" drywall to cover a 36x30" sectio of the upper part of one side wall opposite the showerhead. I felt like it shouldn't matter since I'm also going over everything with Kerdi membrane. I was just wondering if there's any issue with bonding the membrane to the drywall. Will the moisture in the thin set cause trouble to the paper surface? Should I just mix the same ratio and go?

#2 - Thinset brand and consistency attaching membrane

I used Schluter All-Set for bonding the Ditra sheet to concrete floor. But it is expensive so for doing everything else (membrane over shower floor and walls) I went with Mapei Ultraflex LHT SG white. There is a ratio given for setting tile and a more dilute ratio for setting membrane. I just realized for setting membrane the label calls for "Keraply" instead of water. Well I just used water. Should I be worried? I found the consistency to be thicker than when I set the Ditra with All Set. I was definitely sweating and trying to expel excess thinset and air pockets from behind the membrane. I also was worried that I was wearing the membrane down too much as I repeatedly scraped it with a 6 inch trowel. I definitely scraped some fuzz off but actually I believe it's ok.