Absolute Black granite Help needed

[Morti55]

Hi group, I just bought 200SF of 12x12 for my bathroom floor and walls and the shower area and hopefully have enough leftover to use as counter-top in the the kitchen. I have never worked with granite and do not want to make expensive mistakes.
Seeing as the bath is the first remodel I start there. the house is 100+ Yrs old w/upgraded elec and copper plumbing, 16"O.C. stick construction.The bath dims are 9'x5'x7'-6"H. The sub-floor is diagonal plank which I will replace with 3/4"CDX and cement board 1/2 or 5/8" (no transition concern)? I have read about isolating the tile from direct contact with sub-floor movement using Schluter Ditra so the tile actually floats on the sub-floor. I guess in the old days they isolated with sand which may be my alternative as I cant see spending $300+ for a roll for 35SF(floor is 6'-6"x5') of the stuff. I plan on using thinset(Should I use A liquid acyrlic modifier 50-50 water mix?) on the floors and walls(plaster/lath - replaced w/1/2" cement board in shower and 1/2" green board for balance of room) and 1/16" non-sanded grout lines for all. I'm planning on running the tile jack-on jack in a diamond pattern that I think will open the room up a bit as the black will cause the room to shrink - I am going four feet up the room walls and tub rim to ceiling - 6'-6".

Should I:
Back up the Durock? with OSB and vapor barrier in the shower?
I read it is wise to support tiles on the vertical runs the tiles are 12x12 x 3/8".If so how?
I want to round over or bull-nose 12 of the bordering tiles is there anyone in Syracuse,NY area that can do this for me. Thanks in advance for your help. All the Best Marty