I like a 6' width min. Any depth greater than 3' is worthwhile....the more the merrier.

If you can't get the full 6', I think losing 4 inches would not be awful. You may want to put some shallower shelves on either side of the door, if this is a galley-style closet, so the hangers don't poke you as you go in :=)

That will work just fine.

When you say Length - I'm assuming that you mean front to back of closet as you walk in the closet. So the left and right walls will be 129".

When you say Width - I'm assuming that you mean left to right as you walk in the closet. So the back wall of the closet is 69".

If you put hang on both the left and right walls it would be a tight fit to walk thru the closet (ie... hang takes up 23-24" which would only leave you with 21-23" of walk space). However, you could put hang on the back wall and left OR right walls with shelving and or drawers on the opposite wall.

Hope that makes sense and helps.