Hello fellow Bostonian! Even though Schwinn did make bikes in the US all of their stuff since probably the mid 80's has been made over seas...as with all former "US manufactured" brands. A lot of times even just the tubes are cut over here and then shipped to Japan for welding and such.

As far as frame weight goes, it's really just a matter of how much you want to chug up a hill. Where we live a frame like that is probably a perfect ss candidate. I'd say go for it and just save all the parts so that if it doesn't work out you can switch back. I think you're well on your way to a new fixie fellow Bostonian.