I do not have any tiles in my current house but if you think about grout discolouring and looking bad.... then I think that might answer your question. My thought - the less grout the better.

I wouldn't do skirtings . I'd do the floor tile for '1 tile' up the wall ( assume they are 200 x 200 or 300 x 300 -- cut them if 400 or 600 ) . Personally , I'd probably even do the 'silver' tiled areas in that 1 height darker tile too , as it would make the whole room look more 'level' , but thats up to you and your tiler .

Hi there! I'm an Asbestos Assessor by trade and come across these a lot. In the UK these would be highly friable asbestos insulating boards, but here in NZ it's always pinex. No asbestos in these ceiling tiles :-)

Hi there. If the tile you have has character, you could pull a colour from some of that character, for example if the tile had a beige fleck through out you could use a similar beige tile in the bedroom, otherwise just choose something that compliments the tile well to create a soft transition. Then use the colour of the existing tile in the room somewhere, with your bed linen for example or bedside lamp. Feel free to share an image of the existing tile.