If a Chabad-Lubavitch couple decide to live as shlichim (emissaries) in some place far from New York, what's the most common age and location of retirement? Do they tend to remain in their location? Move to Israel? Florida? New York?
Anecdotally, I've heard that it is common for shluchim, as one of their first acts upon arrival in a new community, to purchase burial plots for themselves - thus demonstrating that they intend to remain there for the rest of their lives. Most of them do in fact do so. One example is R' Yehuda Leib Raskin, shliach in Casablanca, Morocco, who passed away in 2004 after 44 years on the job, and whose wife Reizel תבדלח"ט is still running the Chabad House there.
(Although in practice, of course, this isn't always the case. I know several shluchim who left their positions, some voluntarily and some not so.)
Shlichus, like described in the Gemara, means that one is sent on a mission and accepts to fulfill it. The Rebbe sent his emissaries out on their mission (and Shliach Oseh Shliach) to make this world a holier, more G-dly place and to usher in the final Redemption, Moshiach.
This explains why Shluchim do not retire, leave their positions, or make Aliyah to Israel - except under extraneous circumstances, as there is still work to do.
Moreover, Chabad Shluchim take after the Rebbe who was generally opposed to the idea of retirement. Over the course of one's life, whether in business, teaching or outreach, they attain a greater impact and ability to influence those around them. This should not end at 65, or 70, but as long as humanly possible.
With regard to financial arrangements, this falls under the jurisdiction of the respective community as it does with any respected rabbi or community leader.
I know of only one Shaliach who is contemplating retirement due to personal circumstances, and it is widely believed by those close to him that he may well retire back to Crown Heights to be close to his family, but that this is a long way off (he's been a Shaliach for some 20+ years). Other than that, I've never heard of a Shaliach retiring.