The bagpipe is a pipe organ. Same thing. Air-filled bladder that fills pipes with air. But since the bagpipe is meant to be portable, the pipes have to be fingered to change pitch rather than having a a different pipe for each pitch. And I know about portatives and hydraulis organs and all that. I've studied the origins of pipe organs a bit.

////he points out that tal also relates to the pinewood used for their construction////

I said I thought tal might have stood for tail and that was where I learned it was also called a tegelharp. I never said that tal actually meant tail. I was careful not to word it that way. If we're going to get all didactic, let's read what's written not what we want the other person to be saying.

////The cello & bass spikes are floor rests////

You mean like this:

http://www.simorq.org/uploads/pics/36.jpg

////and, in any case, are absent from baroque cellos which are held between the knees much like the viol. Forerunner, is, I think, pushing it a bit as it implies a direct historical lineage.////

Since Arabic instruments as the rebec became all the rage in Europe during medieval times, there's no reason not to consider it a forerunner.