to answer your request for feedback on what would Mcatters like to see in a workshop

I would wish for 4 sessions working (not being lectured to) on the techniques you list in your item number 1, applying them to a few folk songs, and maybe taping the sounds and playing back the audible improvements.

Then I would like a session of working in small groups singing harmony, which is what everybody wishes they could do and seldom get a chance to do much less get instruction on.

I would leave off all the rest, anybody seeking that deeper knowledge can take college classes in it.