Yes, agreed. The general rule is that if you say it as a decimal, the plural form is used. My sat nav frequently says things like 'in point one miles, turn left'. (I would of course never say it like that - I would say 200 yards or something similar.)Yes, but I rarely would.
The only reason I might is if I were compiling a scientific paper or giving a scientific presentation. I would never use this in ordinary speech.