i use "turn right one-zero degrees" or "turn right heading two-one-zero" (no degrees) if i'm asking you to turn a certain number of degrees, i usually don't care what heading you're on and it saves time not needing the 2 readbacks (degrees & heading)
Absolutely. You can find in the PANS-ATM (doc 4444) under 12.4.1.3 Vectoring Instructions:
(...)
d) FLY HEADING (three digits);
e) TURN LEFT (or RIGHT) HEADING (three digits) [reason];
f) TURN LEFT (or RIGHT) (number of degrees) DEGREES [reason];
(...)