Tile adhesive etc

[rotadays]

Hello everyone,
Ready for tiling my en suite now and some advice would be greatly appreciated.
Tiles will be fixed to moisture board walls and chipboard floor, floor very solid and screwed down well no movement at all, would you recommend a sealer?
I will be using 600x300mmx 10mm ceramic travertine wall and floor tiles. I will be fixing the wall tiles 600 wide horizontally in line with each other not brickwork fashion , is it best to then fix the floor tiles the opposite way 300x600 in line?

Also what's the best adhesive for a slow but thorough DIYer I won't be tiling quick so the longer the adhesive remains workable the better.
What depth of adhesive should I use and which trowels to achieve this. Lastly what size tile spacers and are there any you recommend.
Thanks as always

 

[L95]

Has to be powder based mate. I'd say 3 mm spacing and I would personally use BAL CTF4 or Topps own slow flex as I've heard that's quite workable from some local traders. Not sure about Mapei brand slow sets but they are also quite reputable.