Rule Clarification

[Triiz]

-Is the island all FTE?
Yes if no one is sitting on single spawns.

-Are single spawns campable on seafury island?
Yes, there aren't special rules for seafury island. Single mobs are campable in any outdoor zone (see the thread you quoted where Cecily points this out to Llandris, and he responds with the quote I posted)

-If single spawns are campable are you limited to claiming just one (I suspect yes)?
Yes, you can compete for others if you don't leave your camp but you will be competing against the masses for those extras(Multiple places you can sit on a spawn and grab at least one other without moving)

-If limited to camping just one, do you void your claim to that one camp if you run off to pull another mob (or mobs) but are back to your 'camp' in time to engage by the time it spawns again?
Yes, again there aren't special rules for Seafury island

You do not necessarily need to be at the spawn point to call it 'claimed' while it is uncontested, however, if someone else wishes to contest the 'camp' you do need to return to the 'camp -- P99 play nice policy

In my experience, the regulars of Seafury island know all of this. I haven't been out there much lately, but when I used to be out there in the mornings I would sit on a single spawn while I'm doing other things and chuck javelins at any others I might see passing by that are in range, very rarely have I had anyone try to steal the spawn I was sitting on.