Regarding equipment: in the Apostles I've found that cell phone coverage is much better than VHF (though I'd carry a VHF too). I carry my cell and pouch in my life jacket pocket in case I get separated from my boat. In a separate pouch and also in a water tight (small zip lock baggie) I put my bluetooth headset. My thinking is this: If I'm floating out in the water separated from my boat, I'd like to have several chances to call for help. I can get the bluetooth out and voice dial from that to my phone while my phone is still dry in my life jacket. If that fails, I'd pull the phone itself out. Just this year I've started entering phone numbers into my phone before I sail so that I can voice dial a specific location from the headset. However, suspect '911' would get the job done fine too. (Also: if I need to make a call while sailing, the bluetooth earpiece is a hell of a lot easier to use vs use phone.)
I'd also suggest buying a personal locator beacon (PLB). You can find a small one at Amazon. They last for years, can fit in a life jacket pocket and require no charge beyond the charge to purchase. If you get in trouble, they send a signal to a satellite and the coast guard comes out to get you out (or that's the way it's supposed to work: fortunately never had to use mine).
When 444 visits the Apostles, we also now have the luxury of having someone (Todd Bosch) on a keel boat who hangs around us and can offer a hand if trouble arrives. So far the only trouble we've had was running out of wind and needing Todd to tow us to Madeline Island for a cold drink at Tom's Burnt Down Bar....