Can't answer all the questions, but let me try a couple.

I have both a "power of attorney" and a "durable power of attorney" on file with my attorney (but it could also be a trusted friend/relative). Both these documents give the person the authority to act totally in my stead---that includes selling property etc. The difference between the two documents is that in most, if not all, jurisdictions in the US, the standard power of attorney is null and void if you are disabled or medically incapable/disabled. The durable version specifically addresses that condition. I think these documents are advisable for most adults, regardless of traveling overseas or not, and I think it is probably the most important prep you can make. As it needs to be valid in your home jurisdiction, it is easiest to have it done in that jurisdiction. Usually, if not in all cases, the signature needs to witnessed and notarized.

Transferring money overseas: depends on how much and what you need for how long. In most places, your credit cards will work, and you can get cash from local ATMs using your credit cards. There are other ways depending where you are. Western Union can transfer cash to people in several different countries; there are other services doing the same thing, often specializing in dealing particular countries. If you are overseas long enough and in a location where you can have a local Bank account, you can have money wired into your local bank account. Social security will forward you money to some, but not all, countries overseas.

Local laws and regulations, fees, etc. all will affect the details of how exactly things will be done.