If you have the code, and haven't input any code yet, then you don't have to wait. When you turn on the radio and see "CODE", just put in the four numbers and you'll get your radio back instantly.

On the other hand, if you've tried to input the wrong numbers several times (and I won't ask how that could happen), it will lock up. To unlock it (to allow you to put in the correct numbers), you have to keep the radio turned on for two hours. Don't run the engine -- that's a waste -- but just leave the key in and turned to "accessories", the position that would normally leave the radio on with the engine off. Turn the radio on and leave it for the duration. When you come back, it will display "CODE" again, and you can try again.

Sorry I can't help with the SRS question.