I can answer some of your questions.
I live close to 1o de Mayo, one of the places with large quantity of expats, but I live in the ecuadorian side of the street. I like because is close to the river, close to the mall, close to many of my expats clients and also is quiet ( if don't count the roosters),local and cheaper than the new condos along the river.
There's many expats under 50, but is difficult to find them :-)
Just kidding, if you meet with other expats you will find many in the 50's and active. There's also many in the 60's and very active too.
There's mountain biking, but is more popular, by far road bicycle, there's many bicycle stores in the city.
Cars in Ecuador are very expensive compare to the US. A regular car with no extras can cost 4 to 5 thousands more.
There's many places in the city to run, if fact there is an old running tradition in the city and there's many marathons along the year.
There's not a big offer or interest on international cuisine, in fact a couple of shushi restaurants closed in the last months.
There's only one thai restaurant run by an expat, a couple of indians, some chinese ( different flavor than in the states)fast food ones, italinas and many traditional ones.
In general, Cuenca is a safe city. More than Quito or Gauayaquil. I didn't hear of any gang related crime and statistics show crime is lower now. Of course, you have to follow the basic safety rules.
Litter is still a problem but the cleaning service is very good. Grafitti is visible but not that bad and decay is not visible at all. Many parts of the city are old but no decay or abandoned.
Well, your last question is complicated, I heard some complains but I think, in general, locals are happy with the fact foreigners are coming to the city and new business are blooming and the city is improving.
Good luck with your plans