basically those you mentioned although i'm not so keen on including intelligence gathering, disinformation, psy-germ-chemical warfare. dedicated airborne forces would be considered, rather than simply air-delivered.

well, coast watchers, though endorsed by the military, was largely a civilian effort. but since you asked, it feel their usefulness would be limited to intelligence gathering before regular hostilities begin. it wan an informal data gathering system, designed to expand the military's own network. in a steady shooting war, you will have to rely in your regular military recon and intelligence gathering.

keeping to my original course, halsey said coast watchers saved guadalcanal and guadalcanal saved the south pacific. i say wrong in both points. the initial success of operation watchtower was in achieving complete surprise in both the first-day landings themselves and the destruction of the japanese flying boat flotilla. there followed a naval war of attrition that drained japanese human and hard resources. strategically, it diverted japanese attention from new guinea and indonesia but even of guadalcanal didn't happen, the japanese would have reached the end of their line in the other places mentioned, much the same way as the solomons.