Shower Waterproofing

I did a shower pan mud bed a few days ago and have some questions about it. This is only my second mud bed, so I'm not a pro, just an 'enthusiast'. This was made using a 4-to-1 mix (Mapei) with a bonded flange (FloFX):

Question 1: Should the surface be grainy/sandy? I worked quickly to get the mud bed filled and screeded properly. I tamped and floated it with a wood concrete float. There are a few minor surface variations (not sure if that should be a concern).

Question 2: Should I vacuum or sweep off the loose sand/grit? My next step is liquid membrane (AquaDefense).

Question 3: I used ledgers and built up to the bottom of the ledger board to create the mud bed, but as you can see, I was a little low, leaving a ledge at the back and side edges. I checked the slope from the lower part and I am still greater than .25 inches per foot of slope, so I'm not worried about that. Should I grind down the higher part down or should I use thinset to even it out down to the drain flange? The thinset would be .25 inches at the greatest.

Thanks in advance for your help!