1. on the stuff that hangs out in the elements i usually fill it with epoxy. i take the plug end and stick it face down in a hunk of plastilina, (oil based sculptors clay) then fill the backside with epoxy till it fills up. they go for years that way no prob. the downside is if something gives inside the housing, you have to chuck the whole thing and start over.
2. they make a marine version, if i remember the brand ill post it. (forgot) its not one youd recognize normally, and it isnt cheap, but it forces you to make you connections further up the line so there out of the scum, ie. what muddinguy said.