1. Generally that is the total length of the pad
2. Yes, sway cpntrol is always the best answer. Remember trailers are advertised as dry or shipping weiht, and you will never ever tow a dry trailer. Instead determine the trailers GVWR and see if it fits within your desired load capacity.
3. Start looking as a first trailer used. You will get,more trailer for less money. Let someone else take the huge depreciation hit.
4. NO, NEVER ever sign up for some membership club. They are generally a simple time share that you wwind up on the hook for a really long term.