I have a few of questions

1) I have wood sitting in the rooms they will be installed in.... i know i need to acclimate the wood first, but how long can i leave it?

2) I have 3 rooms that connect to a hallway that I want to lay down 3/4 x 3" maple. what is the correct way to transition from the room to the the hallway?

3) In at least one of the rooms, there is a gradual sag and right in the middle(running perpendicular to the joists) it looks ok going in the opposit direction. I created a grid with some nylon string to see where the low/high spots are. There is about a 3/8"-1/2" dip in the lowest spots. I was planning on sandwiching a piece of 1/4" ply wood or something similar in between 2 layers of roofing felt. Then feathering the edges with more felt or roofing shigles....is there a better way to do this?

Oh and this site has been the most helpful out of all i have visited. Thanks to whoever created it.

Chano