mail arrives at our local "Post Office" with very few problems, it's just slow.
as for finances, we kept a bank account open in the US, as PayPal and other online purchases can sometimes be difficult to make.
Online Shopping Carts don't seem to like 'Ship To:' addresses being different from the 'Bill To:'
some people use "Forwarding Services" to handle their purchases, and others have 'mules' bring stuff to them.
we keep a mailing address in the States, and have our mail forwarded in a box by a family member, along with some new books every few months.
books are duty-free, as is mail, anything else will probably cost you for customs duty...
for Social Security, we kept the direct deposit in the US for the first few years, and withdrew money locally at the bank... but after a while the ATM fees really start to add up, so, I had the SS transferred to Belize this year.
Atlantic Bank is the only bank approved in Belize for Direct Deposit, they use a correspondent bank in NYC.
the money generally shows up in my acct a day or two later than it would in the US... it helps to keep an eye on a Belizean calendar, the holidays are different here, and that can cause delays.
life insurance, we don't carry it any more... it's just another expense that eats into one's paltry SS check.
the CDs and brokerage stuff have long been closed, and the money spent on building a home, guesthouse, storage, and various farm buildings, so that's no longer an issue.
note, this info is for inland living, things are much more civilized in A/C.
good luck with your planning, and remember, research is everything, and you'll get different answers to your questions, it's up to you to decide which one is the right one, LOL