"are there hard and fast boundaries between other genres of newly created songs and contemporary folk song?"
Nobody is attempting to create hard and fast anything any more that they are bandying '54 about
As to what a folk song is - as a researcher, you shouldn't need to ask that - it's part of the job description
"And to those that don't accept the term 'contemporary folk song' what alternative are you offering for say MacColl's songs and similar?"
How about contemporary songs using folk forms and functions
These have never been a problem as far as the clubs are concerned (only when researchers who should know better appear not to be able to tell the difference between newly-composed songs and the real thing -
The real bone of contention is the lack of connection between real folk and what has become a large block of material that has nothing whatever to do with or sounds like folk   
Jim Carroll