OK, Let me start an answer for Question #2. When I go snorkling, I
make sure my bathing suit has pockets. In the pockets, I keep several
sizes of zip-lock bags. Since what I look for (the Epitoniidae) are
usually rather small, I can put several in any size zip-lock bag.
Then I can put "interesting other" in a separate bag. If you find
something really too big for bag or pocket, paddle back to boat or
beach with it. Separate and dry your catch later. For live material,
Zip-locks in several layers will help contain odors when the live
material stops being live.
             Art