Installing mirror into tile recess/flush with tiles. - Tile Advice

[fandyman]

Hi,

I am planning to install custom made 6mm thick mirror (1.7m x 1m) into a tile recess. The mirror is about 25kg. The tiles are protruding out about 1.5cm - 2cm.

Thinking to glue with pinkgrip and then plug & screw 6mm tile backer boards to add thickness to the wall before gluing the mirror with mirror glue.

I am also planning to finish the top and bottom of the mirror with an H-Joint aluminium tile trim (see a bottom section example on the attached photo). The bottom tile trim will be glued to the tiles/wall before inserting and gluing the mirror with mirror glue and the insert and glue the top tile trim afterwards. Alternatively I can glue the mirror first and the insert and potentially glue the trims?

My question are:

1) Is it ok to go with the 6mm tile backer board in order to make the mirror flush with the trims and tiles
2) What installation order should I take: bottom trim - mirror and top trim or rather install mirror first on support and wait for it to cure and then insert and glue the trims?
3) Should I be gluing the tile trims to the wall/tiles as well? If so can I use pinkgrip as well or maybe I can use mirror glue or sth else to glue them down?

Many thanks,
Andrew