Extreme in the case of deca would be 1000+ mg per week, so you're in the clear

Deca should be taken weekly so do test on Mondays and Thursdays, and Deca only on Mondays.
We still don't know your stats and cycle history though. I'll say as I've said in many threads already, that you're probably adding too many different AAS. A person can go a long way with test only, let me tell ya.
As for that last part it doesn't matter if you stop deca before you stop test, or run test 2 weeks longer than deca, as it would practically be the same thing, i.e. test running longer than deca.