Sanding the wall before tiling? / Edge profile for tiles?

Hello everyone,

now a quick question. I want to install tiles here in my small U-shaped kitchen.

Question 1: Do I need to sand the wall first or will the tile adhesive stick as is? (The wall is rough and not treated with anything)

Question 2: At the outer corners (marked in black in the photo): Should I leave the edge open on the last row of tiles, cover it with a silicone layer, or use a profile strip? If using a profile strip: L-shaped or T-shaped?

Thank you very much in advance!

A bit late, but I hope it still helps. Tile adhesive also sticks to rough plaster, possibly a primer is necessary. L-profile if tiling only on one side. For the questions, it would be better if you find someone who has done something like this before.