I dont know if this is correct, but heres what I would try for the SEAD flight-
Set your first target waypoint near the SA-11. Make sure your SEAD flight has no SEAD task in the advanced box. have them perform enroute task, or perform task and attack the specific radar. Create a SEAD task in the advanced waypoint tasks with a start condition of "is user" and put 1.
Create a trigger that when tageted radar unit is dead, flag 1 "on". The unit dies, flag 1 switches, DEAD aircraft flip on SEAD mode. Theres other ways including setting priorities on the waypoint actions, I believe its in the GUI manual. Good luck.
Edit* begins in GUI pg. 91.
Edit** if you want multiple units dead then just put those in the trigger to flip flag 1.