ᐅ Sanding Walls Before Tiling? / Edge Profiles for Tiles?

Hello everyone,

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

Question 1: Do I need to sand the wall first, or will the tile adhesive stick properly without it? (The wall is rough and untreated.)

Question 2: At the outer corners (marked in black in the photo): Should I leave the edge of the last row of tiles exposed, 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 this still helps. Tile adhesive also adheres to rough plaster; a primer might be necessary.
Use an L-profile if tiling on only one side. For your questions, it would be better to find someone who has done this before.