A.c: Take a look at our updated test information on bed wood finishes.
http://www.mar-k.com/wood_finish_update_12_05.html We are testing 10 finish systems and previously tested 10 others. Marine Spar is not the best for long term durability in the weather. It stays pretty for a long time if the bed is protected. We have varnished bedwood in the showroom display that has been there 10+ years and it still looks great. In continuous outdoor testing, the same finish lasted only a few months.
If you have some time before doing the bed, we suggest that you select a finish and do your own test to see which is best for you. Put it in your own real world situation and see if it holds up.
Mar-Ktech