>1. Cost of living in Puerto Rico is quite high. Expect to pay roughly double for the same foods you would anywhere else in the US, in terms of eating out OR the grocery store.

This includes online shopping. UPS and FedEx's rates for delivery to PR are much higher than on the mainland, so almost all sellers that use those carriers won't ship to the island even if the item is small enough for USPS (which does not charge more). Same with Amazon, although there is a chance a third-party Amazon seller will.