easily fixed: make the path on a surface a very small ribbon will suffice! Its quite easy to do. And a s a bonus you get real fotation controll!
this can be quite easily scripted. Especialy if you allow yourself some latitude in doing things and create a extra empty transform. Now just rotate the transform and parent. if you need it other ways then unparent and rotate. But yeah animating this is not so fun. Altough it can be done since the scales translate to the three axes!
Umm... you just said rivet mel does this... so why do you need it in the firstplace. Its not like the rivet mel aqctualy does something maya want ever designed to do. it just combines things differently. (most maya scripts do, its not like they developpers have or should have done all the possible variationa... hey you would have 50 mensuets instead of 5 then!)
Yeah, but then it wouldnt be an instancer! The idea behind the instancer is to make a huge number of objects with minimal overheads. Now if you made this work wich you could than it would consume wast amounts of memory and 1,5 gigs very fast gets to be peanuts.
Make a serch on boids.
But it would offcourse be cool to have massive 
PS no one actualy logs this thread so go to the side suggested in some post above or to aw... Anyway the wish list thats going on is pure [censored] just because most users requast redundant stuff.