Its not going to make any difference. The only reason you want to let it sit for 45 minutes is so that it is dry enough to buff off. Any more time than that and its just going to collect dust and bugs that could damage your paint when you try to buff it off.
That would probably work, but I still don't see the point. What exactly do you believe will be the up side of leaving it on the car for a week? It would probably cure better if you buffed off all the excess. What you are thinking of doing could actualy impair the sealant more than helping it.
Yeah I agree that would be a bad idea. It can only hurt, not help. Also, Ive never washed a sealent off but I would imagine it would be difficult and probably streaky.