As to point (1):
Scrivener has no built-in way to give you word counts per character.
However, I wrote a pair of scripts to produce word counts for each character in a script. One works directly on script text copied from Scrivener. The other (which is more script-format agnostic) analyses a script compiled to Word.
I recently posted them both /in this thread/, though the user I did this for did not manage to get them working.
Unfortunately, both are written in Applescript, so not useable for you on Windows. Still, the algorithm behind the latter script could easily be worked as a Word-based script. So, if you are into scripting Word, that could be a solution for you.
As for your second question (which deserves a fuller answer), there would be various ways to get such a result. How you might approach depends on whether this per-actor-part guidance can be relied on to live in paragraphs separate from the dialog (and other) text. If, so, achieving your end is pretty straightforward and just involves these ideas: Scriv lets you slice your script up into separate documents seamessly, documents can be assigned keywords and labels, compiling your script can be restricted to just those component docs that have certain keywords or label.
To flesh that out a bit: Scrivener lets you split your script up into as many document pieces as you want and easily fuses them on the fly. Thus, your guidance chunks can live in their own docs while still remaining in their interstitial position in the script. Since docs in Scrivener can be assigned keywords you would then be able to do a simply search which would yield just script text plus one actor’s guidance. This could then be compiled to output, and so on for the other actors.
If your guidance is not always in its own paragraphs, but must sometimes occur in-line with dialog (or other) text, then your task would be trickier.
—gr
p.s. Sounds a little like hell to have a group of actors who don’t have a common pagination in their scripts. But, hey, it’s your crazy!