1) Only as difficult to find as necessary to keep it from muggles. Going to the water and doing the paddling is the challenge. The hunt need not be difficult.
2) Depends on the surroundings. I don't mind landing if there's a reasonable place to land and search. E.G. - Keechelus Crossing II is a better cache for having to land. Lake Alice is great to do from the boat.
3) I'd still make the trip for a virtual but a micro or small container is better.
4) For me it's about the paddle. I recently logged a DNF at one of your paddle caches. But I still had a great time being out on the water and I knew I had been to the cache location even if I didn't bag it. That was a much more satisfying trip than finding a tough micro in the woods (I hate those).
No worries, mate. We appreciate any cache you give.