You are too picky. You guys have been working together and know each other well. Usually you will get along in a marriage as well. My husband I used to be workmates. I think it is the best case to marry to your friend.
And it is not too late to have kids. If you decide to date him go out for half a year and then plan a marriage then kid.
Dating someone on line is more risky at this age and will take lots of test and failures so go with the Taiwan guy!
Being single has some advantage but eventually we all need to settle especially you are settling with a long time friend. Don't let this guy go. Good luck!