#2
Probably
Psectrotanypus varius -- it looks like North American
P. dyari and you have only one species of the genus in Europe that I know of.
P. dyari is tolerant of pollution and so is widespread and common in America.
#3
Thanks John, as I see they had already attracted some attention before:
http://www.diptera.info/forum/viewthread.php?forum_id=5&thread_id=33741&pid=150110#post_150110
and
http://www.diptera.info/forum/viewthread.php?thread_id=33774