A lot of this depends on the context: if there's a frame of reference, most would understand "Pos" for "Position". Without a frame of reference (ie the user is not expecting "location-y" information) they probably wouldn't
Position: Pos
Would likely be understood in a reasonable context, but be wary
Coordinate: Coord/coords
Would be understood in almost any circumstance
Radius: r
Would be understood if clearly within the context of "talking about circles", not otherwise
Circle: CRCL, Cir, Circ
Crcl Would again likely be understood (or rather, would be "worked out") in context, the others probably not. You're only saving two characters, however, and it's probably not worthwhile considering it's not a particularly widespread abbreviation
Deviation: Dev
Probably not, unless within a very clear context AND a mathematical audience
Region: Reg
Maybe, but I wouldn't want to rely on it
Intersection: Int
Almost certainly not. Int almost always refers to Integer within a programming environment
Reference: Ref
Would usually be understood in most environments