Considering retiring in Taiwan

Wow, such a huge topic.  Im not sure where to start, or even what to ask!!  So, a little background first. 

Im Caucasian (U.S. citizen), my wife is Taiwanese (dual citizenship).  We met in Taiwan back in the late 80s when I was teaching English; weve been in the U.S. since 1990.  Now, we are thinking about moving back to Taiwan as an early retirement (55 for me).  Retiring at that age in the U.S. would be a huge financial stretch for us, but between the NHI in Taiwan and a lower cost of living (we are able to live with family), we THINK we might be able to swing it in Taiwan.  Thats what we're trying to figure out. 

I would like to do some work while in Taiwan, and I suspect the only thing available to me would be teaching English again (and my Mandarin is terrible, and Taiwanese non-existant).  But I need to evaluate the feasibility of this venture as if neither my wife nor I are working. 

We are visiting Taiwan for 3 weeks in November when we plan to really evaluate this idea, but Im hoping to get some info and insights before we go  thats a lot to digest in 3 weeks, and we hope to still do some visiting and vacationing while there (I havent been back in 15 yrs).  So, any input would be greatly welcome.

I know A LOT has changed since we left in 1990.  Im definitely not the same person, and from what I can tell from afar, neither is Taiwan.  Not to dwell on the war stories, but it was difficult for me when I was there in the 80s and I can only imagine how different it would be now.  Our town is a smallish rural place in the hills outside of Taichung.  Back then there was no English-language T.V. to speak of, no personal computers, no internet/email/skype/etc. (of course; it was practically the stone age!!), international phone calls were incredibly expensive, English newspapers were few and scarce, and I was the only non-native for many, many miles.  And then there was the overwhelming pollution and the generalized street-level chaos, both of which I understand have improved greatly. 

But, I digress   So, a couple of specific financial questions (Im focused on the financials because if we cant get that to work, the whole plan is dead..and I keep working for another [xx] years) :

Regarding the NHI for spouses of Taiwan citizens (and assume Im unemployed). 
1)    How much does it cost?
2)    Will the insurance cover me while out of the country (say, on trips back to the U.S.)?
3)    If so, how long can I be out of the country before the insurance lapses?
4)     Anything else I should be aware of?

Regarding work: 
1)    Heck, Im an old man now, and keeping in mind that we will be living in a relatively rural area (Dongshi  東勢區), what are the prospects of finding ANY work?

Other financial considerations
1)   Are there other taxes, fees, or other cost of living expenses that I should take into account?

Thanks much for any input you have.