Usually it is better to buy a lift that is longer than the deck of your boat. This allows you to use the bow stops to help you dock your boat. In addition, you will then have a longer lift for the bigger boat you will probably buy in the future..
2.
It is acceptable to use a shorter lift and will save you some money. However, it is a little harder to dock on a shorter lift. The front and the rear of the boat should hang off the lift equally.
Old Style, Fluted or "Ruffles" Sided Winches: Must be modified before they can be moved. Otherwise the winch will be mounted upside down and the lift won't stay up.
Modification: Remove the mounting channel from the end of the winch and reattach it to the other end. This requires removal and reinstallation of 4 carriage bolts. Make certain that the slot in the mounting channel stays opposite the drum.