Yes, finish off the wall so it is complete,

so it looks great with or without your current size of microwave.

Are you talking about the unit that is in the cabinet? If so, I would not.

Yes, the part justbehind the microwave. above that there are caninet doors

Can likely be done and assuming location is above stove, but consider that microwave may protude a little further out due to tile thickness behind it.

No the location is where the microwave is now.

Sure! Don't have to but it might look nice. Whether or not it's worth the effort depends on the tile.

I would not tile it. You already have a finished white-painted cabinet back which blends in with the rest of your cabinetry. I think tiling it would be too much adornment and would look odd because it's not expected.

Thats a good point actually. i painted all the cabinet boxes and left this part unfinished for tile. ill paint it

I would . im tiling behind my fancy coffee maker that is moving to the space of my old microwave. im ising a small accent tile that is featured in my backsplash

I would not. The MW shelf is part of the cabinet. Also, I would remove that cabinet and shorten it up to match the other cabinets. It will look much better, give you more space between the uppers & counter top, better access to the outlet (which looks like it is partially covered by the cabinet--code violation if so), look & feel a bit less crowded and still leave ample room for the MW.

Often the backs of cabinets is really thin material and not suitable for tile. When you adjust the size of the cabinet--there won't be much tile visible anyway.

This is the kind of small kitchen made for a microhood...

We looked at shortening the cabinet actually. the issue is its designed this way so the corner cabinet door can open…

Yes, I see that now. Should have realized that. Bummer.