For Instrument swapping, I use Duxa UI (found here:
http://www.project1999.org/forums/sh...ad.php?t=28335), which includes primary/secondary weapon slots at the top of all bags and on the right side of the primary action bar (along with the full set of 8 general inventory slots). Having these slots handy allow me to quickly grab weapons with my cursor and swap them around as necessary to always have the proper instrument equipped for the right song.
As far as singing (casting) macros. I opened up another action bar, made eight 2-line social macros (line 1:
/stopsong line 2:
/cast # where
# is the spell gem 1-8), and put them on the second action bar, then I just mapped the action bar's first eight button positions to my keyboard and then hid that action bar.