Just to add what works for me (USA Citizen) to the info mix:
Address: USA authorities and many businesses don't like lat/lon as an address so I maintain a USA mailing address at (what is now) a UPS Store. Have used this address for many years and it works fine for almost everything. Consistency is good. I also maintain a physical address, because for some purposes a PMB won't work. Issues to be aware of is how the address you choose may effect your tax status and things like jury summons (some jurdictions take these more seriously than others and may not be amused if you no show).
Mail: I have important items scanned and emailed to me to avoid delays. Other stuff gets sent to me once a month via mail forwarding/consolidation service
(service used depends upon which country I'm in).
Residency: Some IRS rules, and now the ACA, depend upon IRS tests for whether you reside in the USA or not. Legal
residency in a foreign country is the trump card...no doubt about your legal
residency that way. I established legal residency in Guatemala
(easy). Some gringos make this hard by trying to do it all themselves. Hire an agent in your country of choice and in the USA (or home country) and make this dead easy.
Driver's Liscence: Handy if you do much land travel (we do a lot using my Jeep) or want to rent a car, or use for ID (many places have accepted mine for uses like ID verification for CC use). Many jurisdictions want a physical address for your DL.
: Most authorities, and some business, are easier to deal with if foreign location does not come up at all. So, I have a USA phone
number via Skype, that plus my USA address means as far as they know I'm in the USA. I use call forwarding on this number to my local cell (wherever that may be) so I only have to give out one number and just change the call fwding. Also have voice mail on this number w email
notification. I also maintain a USA fax # (eFax) for the same reason.
IP Address: Some web sites behave differently, or block you entirely, if you have a non-USA IP address. I used VPN to get around this.