There are 5 major issues to consider:
- Where to live that supports 1-3
The first issue is something that is very personal, and ultimately about how much money you have, access to money via pension, savings, etc… Also, it is about cost of living. Do you eat out a lot? Cook at home? Enjoy new cuisines? Are your hobbies expensive? Cost of living differs for everyone. After talking a fair bit with many people, and after recently traveling to Taiwan after being away for 10 years or so ( I lived there previously for about 8 years), for my family we need about $80000 -100000NT (approx. $2600 - $3250 US) a month to live comfortably in the Taipei area. This does not include schooling costs. However, we eat out a fair bit, but at local places that are cheap, and only eat at Western style places once every week or two.
The Visa is the biggest issue really, in that Taiwan does not have a retirement Visa. It is largely an issue of what you want to do and how much you want to work. If you are flexible, Taiwan has a lot of options. You can teach English minimally (15-20hrs/week), and get a Visa, and do what you want for the rest of the time (as long as money is not an issue). You could open a business, be it a representative office or a full-on business in Taiwan, but neither of them are relaxed part time gigs, and would require a lot of time and money invested. Finally, if you have $200000 US available, you can get an investment Visa, that requires no work whatsoever - it just needs to be put into a Taiwan based investment of some sort. All of these visa is will give you a residence visa called an ARC (Alien Residence Certificate)
It is important to note that Taiwan does not allow part time private work while on any type of regular resident Visa. After five years of residence through a work, etc. (residence) Visa, you can then apply for an permanent residence visa (APRC) that allows part time gigs.
As for schooling, it is a huge issue. International schools in Taiwan are ludicrously expensive (think $20000+ US /child), so for us they are out of the question. Do your kids speak Mandarin? If not, how old are they? If they are younger (under 8 or so) they could have a chance at learning Mandarin and integrating into local schools. If not, your only option is homeschooling, which has its own set of pros and cons.
As for location, this can be debated forever really. For me, it can be summarized as follows: Taipei is convenient (especially with the MRT), culturally vibrant place which has a lot more of the things Expats might need (foreign groceries, expat community, etc.), but it is more expensive than other places. However, the further south you go, the weather gets better, but the pollution gets worse. The east coast has beautiful nature (and low pollution) but with it comes more typhoons and earthquakes and less access to Western conveniences with the small sizes of the cities there. But the East as a whole is a fair bit cheaper for rent than the West coast, and a lot cheaper than Taipei. I am not sure if the east coast had any International schools though (there are some in the cities in the West coast outside of Taipei, for a slight bit less than the Taipei schools’ ridiculous prices).
The final point, language, is really one of personal tastes. You speak some Mandarin, but how about the rest of your family? Do they want to learn? If not, it will be hard long term, if not impossible. But some people do manage to get by without learning Mandarin at all and live in Taiwan for decades. So like I said, it is about personal comfort levels with language (or not knowing one).
It is important to note that I don’t consider “retirement” for me to be dropping off the Earth and herding alpacas or anything, I just see it as the ability to do what I want instead of my current incredibly high stress, life consuming (60-70 hr weeks), albeit high paying, job. And Taiwan is the perfect place to keep doing the things I love, in an interesting, beautiful, and low-crime place. It also allows me to put down roots and get an APRC that will allow my family to live here with me as well, and doing what we want to do. Not many countries allow permanent resident visas for retirees, and neither does Taiwan really - but with working the system a bit, it is possible to “retire” in Taiwan.
Sorry for the long response, but it sums up my research over the last couple of years in one post, for any who are interested.