When putting in an application to a co-op for board approval, I have
seen one of the requirements as being the actual contract of sale.
Does this contract of sale need to be signed?

I am interested in knowing since a signed contract would require that I
pay up legal fees before hand, and could present a downside risk on
making the purchase since if the board does not allow the approval to
go through, then legal fees consumate the loss on the deal.

Does anyone have any information on this and/or perhaps any pointers to
tips on how the whole purchase/sale process works, specifically with
co-ops.