Kitchen Floor 12 x 12 job

[red owl]

I'm doing a second floor condo kitchen, 6' by 9' of tile area. The surface is gypsumite (poured) over plywood. I'm going to use 12" x 12" porcelain tiles. I've put down the tiles (loose- not set) and walked on them. Floor seems level.
Questions: 1. I was told to seal the gypsumite, one source said MBP but another said Red Guard would be better. Any thoughts appreciated. 2. I was thinking of a diagonal pattern but in putting down the tiles (loose) it seems I would have to make a lot of cuts. I'm now thinking a regular pattern. 3. On the mortar. Use a 1/4" by 3/8" trowel or something else? I was going to space 3/16" and bought some rubber X type spacers. I was going to leave 1/4" against the baseboard and fill with caulk.
I have a tile snapper I used on 4" x 4" shower tile. Is there any way to make an L cut with the snapper or do I need to rent a saw?
Right now I'm shifting the tiles around to try to get the best spacing, minimize cuts. etc. As with most things, the walls are perfectly square so I'll have to fit in a lot of tiles.
I've been told I should use Versabond thin set mortar. There is an additive you can use instead of water (worth it?)
All help appreciated.

 

[Time's Ran Out]

Most is lost in translation !

 

[Albert]

I'm doing a second floor condo kitchen, 6' by 9' of tile area. The surface is gypsumite (poured) over plywood. I'm going to use 12" x 12" porcelain tiles. I've put down the tiles (loose- not set) and walked on them. Floor seems level.
Questions: 1. I was told to seal the gypsumite, one source said MBP but another said Red Guard would be better. Any thoughts appreciated. 2. I was thinking of a diagonal pattern but in putting down the tiles (loose) it seems I would have to make a lot of cuts. I'm now thinking a regular pattern. 3. On the mortar. Use a 1/4" by 3/8" trowel or something else? I was going to space 3/16" and bought some rubber X type spacers. I was going to leave 1/4" against the baseboard and fill with caulk.
I have a tile snapper I used on 4" x 4" shower tile. Is there any way to make an L cut with the snapper or do I need to rent a saw?
Right now I'm shifting the tiles around to try to get the best spacing, minimize cuts. etc. As with most things, the walls are perfectly square so I'll have to fit in a lot of tiles.
I've been told I should use Versabond thin set mortar. There is an additive you can use instead of water (worth it?)
All help appreciated.

As stated by my esteemed colleague too much lost in translation.