If it's face brick I would use a grinder with a cup wheel to grind the entire surface in case the brick has some sort of finish on it that's not compatible with tile glue, then prime it with Davco Ultraprime or Ultrabond and use SMP Evo over that.
SMP Evo can be built up to 19mm thick which should accommodate any uneven spots in the brick work, alternatively but a screed coat on first, let it dry (24 Hours) then tile.
Rectified tiles with a porcelain base are very hard to mitre I would recommend you use a tile trim, maybe brushed Aluminium.
2mm to 3mm joints is standard for rectified tiles.
Also make sure after laying the tiles they are kept cool, no hot afternoon sun beating down on them, cover with a white drop sheet for 24 hours.