We have never been able to get our electricals to work properly. We are on 220v and Jamaica is 110v. Even with adaptors, hairdryers, straighteners etc didn't work. I suppose you would have to get some sort of voltage converter.
After four visits to Jamaica, we have given up on electricals. I now have a set of straightners from the US which work perfectly because they work off the same voltage.
Just go with the flow - there are hairdryers provided. Shaver points are okay.
Yes, you can charge up your phone - no problem, also camera batteries, ipods etc. Problems arise with anything with a motor in it (hair dryers, hair stylers etc) or anything that needs to get very hot (straightening irons), with these you will need dual voltage ones or buy a US model like Faraway has.