Can't give an authoritative answer to your first question, Dave, though I think I know what it means -- but re. question two, you're absolutely right in saying that 'gin' means 'if' and they are singing 'win' meaning 'want' but the final T has melded with the T of 'tae'/'to'.

If I have time, i'll check with the singer himself, Tom Spiers, for an explanation.