Your interisland question has two answers depending on which airline you fly.
If you fly HA then the interisland portion is not bad and you don't have to clear security again if you use the "Wiki-Wiki" shuttle ( I always giggle when I see this at HNL...)
Anyway, if you use one of the other airlines, the terminal is tiny, crappy, has lousy information etc., etc. and you will have to clear security again.