awwww man you spoiled the fun. I wanted to watch all the guesses from the 'mericans
My experience with this sort of thing is that you beat yourself up for a couple of weeks, back off and recover and then resume a normal type training plan. You couldn't possibly do this more than a couple of times a year and not get hurt or worn out.
You'd maintain your gains in strength as long as your new program reflects the increases. For example if you are squatting 150 when you start and 170 a month later there is no point going back to the weights you were using before the program.
as far as muscle mass, i'm not so sure but i've stayed above 95kg since last year even on a fairly low volume program.