'Ferlie' is 'feller' in a version in Nigel Gatherer's 'Songs and Ballads of Dundee', p. 60, 1986. Gatherer in his notes cites a sequel by Matt McGinn of 1968 where it is 'fellae'.

Kelvin Ha' I don't know for sure, but think its a place name, as in "The Bleacher Lassie of Kelvinhaugh".