Digital BW, The Print

Yeah, I'm back... ;)

I've read a lot of different recommendations on the "optimum" or 
"correct" resolution your (photographic) pictures should be for inkjet 
printing.  I've been using 300dpi (in the print), since that seemed 
like a good average judging by most things I've read.  My printer is 
capable of something like 4800x1200 dpi according to its specification, 
but I gather that that is more or less irrelevant to my concern.

The reason I'm asking is this: I downloaded a (digital capture) colour 
test target (sorry, OT ;) which was a file at 7x10" (for printing on 
8.5x11" paper) at 360 dpi.  I printed this on glossy pro quality photo 
paper and the result is absolutely astounding.  Both resolution and 
tonal nuances blew me away.  However, when I've printed my own (scanned 
film) B&W prints, I haven't been able to see much difference between 
200 dpi or 300 dpi, and I've never tried more than 300 dpi.

My questions are these:

	* Is there a way of calculating optimum print resolution (say 300dpi), 
given
	the printer's resolution (say 4800x1200)?  I'm guessing that the 
dithering
	algorithms need something to work with.

	* Should I use a different print resolution (say, 250 dpi instead) if 
using
	black-only or greyscale printing?

	* Is there a difference when working with digital cameras vs. scanned 
film?

	* Is there a difference when working with matte papers vs. glossy 
papers?

	* Is the lack of difference between 200dpi and 300dpi in my own 
scanned film
	(400 ASA B&W negative or B&W C-41) poor technique on my part?

	* Who's right? ;)

M.