Promotion wage increase?

Hi, basically im playing as barnet fc and im about to get promoted and i have alot of players who will be getting massive wage hikes

so basically i wanted to know...

roughly how much i can expect my wage budget to increase?
might my budget not increase?
if i dont use all my budget will it decrease when promoted?
if i dont use all my budget will it decrease even if i dont get promoted?

thanks for any and all help

I have 2 seasons with Maidenhead Utd (Blue Square South).

Before promoted, my budget was around 2,5K pounds
After promoted, the budget is around 65K pounds.

So, I think the budget must be increased by the board.
For your question 3 and 4, I can't answer it yet as I haven't finished my 2nd season