Network Access Control and Migration from SEPM 11.0.6 to 12.3

Hi

we are planing to migrate from SEPM 11.0.6 to 12.3. but before that i was looking for some answers. i have seen that 11.0.6 also support network access control but i havent seen that tab in SEPM policy or the client so i can i activate it in 11.0.6.

also i wana know can i import all the policies  from 11.0.6 to 12.3? wont there be a version conflict? also if i change the SEPM then do i have to go to every client to  uninstall the client of 11.0.3  and then re install the client of 12.3 or is there a way that i got simply upgrade clients from SEPM?

regards