"If it matters, employment is not a huge problem...I'm more interested
in questions of residency status, tax issues (do I pay taxes there or
in the States, for instance), qualifying for health care, and so on...
again, any help gratefully recieved."

As for taxes, you need to look up something called the "double taxation
treaty" with the country or countries that you are considering.
Basically, if you are outside the US for 330 days out of a 365 day
period, you can exempt the first $80,000 of your income during that
365-day period from US taxes. (You don't have to spend 330 days in the
country you are living in, just any country besides the US.) Then the
double taxation treaty determines how much of your income is taxed in
your new country of residence (usually 10% or 20%). The end result is
usually that you wind up paying far less in taxes as an American
expatriate in Europe than you would if you were still in the US.

You need to check with the immigration department of the country in
order to see what the deal is with work visas or residence visas. In
general European countries have been making legal immigration more
difficult, but if you have special skills (e.g. information technology,
health care professional) you might be able to get a work visa. In the
case of Japan, you can go there for three months on a tourist visa,
look for a job, and then get a work visa. I don't know if European
countries allow that or not, but it makes things a lot easier.

Italy and Ireland have a provision for citizenship based on ancestry
(Germany used to but no longer does since they were getting flooded by
people from Eastern Europe who were like 1/8 German) - I think you need
a grandparent born in one of those countries. If you can get dual
nationality with Ireland or Italy, you can live and work anywhere in
the European Union.