The following site has about 350 MIDI's of traditional tunes, including Skye Boat Song, but not the others as far as I could tell.

http://www3.islandnet.com/~btaylor/homepage.htm

PS - As a recent, but very disorganised collector of (mostly trad) MIDI's, it is evident that some renditions are much better than others. What doesn't help is that file names will often be identical, e.g irisheye.mid, for quite different sequences. One version might be musically interesting but omit the rarely sung prologue (or vice versa). I know vaguely that MIDI files can contain narratives, but how can you view this without going through the full routine of opening each individual file. I am not a librarian by nature!

Regards John