There are no definite answers to your questions. I am hardly the expert, but my experience has been as follows:
Surveyors are NEVER going to assume any responsibility. They will give you the survey and the "benefit" of their opinion, for what that is worth, but they will always shy away from any responsibility. So, the trick is to find one that (a) knows what yhey are on about, (b) does a thorough job, (c) is honest, and (d) doesn't charge like a wounded bull. Ask around for recommendations (do not ask the seller, nor the seller's broker).
$20-$25 per foot sounds expensive to me. If the guy takes 4 hours to survey a 40' boat, thats a helluva an hourly rate. I would be hoping to get away with significantly less, but again bear in mind, you want your surveyor to do a thorough and professional job.
My experience was, with regards to both (a) the costs associated with getting the boat out of the water
, and (b) costs associated with a test sail, that the seller pays those costs, initially, up front (because they are local), with the understanding that you agree to pay for them if you decide not buy the boat, except in the case when the test sail or the survey comes up with reasonable (and previously undisclosed) grounds for not buying
the boat. If you buy the boat, the cost of slipping and test sailing are subtracted from the sale price
. That was my experience, but it may well not be standard. I advise you to speak to some local brokers, who will tell you what is the normal way of things where you are.