Hello Renjith,
For point no1 You can control this using user-exit ILOM0001. Here few lines like given below restricts users from creating F/Locations of other Labeling system.
IF sy-uname = 'ABCD_XYZ' and data_iflos-alkey <> 'D' .
message: 'You are not authorized to create F/Locn in this labeling system.' type 'E' display like 'I'.
ENDIF.
This throws error pop-up if the user (ABCD_XYZ) authorized for D labeling system tries to create a Functional Location in other Labeling systems. Please note that this is the restriction at the time of SAVE event. If this solution suits to you, you may need to create a Z table for userID vs labeling system to be used in the code above.
For your second question, to my knowledge: yes we rename f/locns manually and individually. So far never came such mass requirement.
Hope a part of this info helps you.
Regards
KJogeswaraRao