Welcome to the group, Patterson! The ideas you listed sound good.
I would not neglect to teach the kids important vocabulary, for both the
camera/darkroom processes and for looking at photographs--elements and
principles, etc. I'd show them lots and lots of examples of good photography
and art historical examples, like Alfred Steiglitz and Ansel Adams. Help
them learn to categorize photographs in various ways. Let them decide for
themselves what THEY think is beautiful and valuable in a photo. Libraries
should be able to provide good books with images to share with them.
Even 1st-3rd graders like learning "grown-up" vocabulary words--they can
digest a lot more than most people think if it is thoughtfully presented.
You can discuss traditional film versus digital. Look at various
photographic papers (glossy/matte).
For a studio activity, perhaps the students could colorize black and white
photos that have been Xeroxed? Or perhaps you could even find somewhere a
bunch of discarded b&w prints, like from a high school or college newspaper,
yearbook, or photography class. I remember that when I was in 8th grade or
so, I took a workshop on colorizing b&w photos, and I though it was one of
the coolest things I'd ever seen.
Another studio activity, for the price of a roll of packing tape and a
magazine would be packing tape transfers from glossy magazine images (travel
and garden magazines have GREAT images for packing tape transfers). This may
be diverging too much, but it is a fun and cheap activity.
You could also spend a session or two on presentation--the students could
design frames for their best photo(s). You could examine the scrapbooking
craze. Have them do a painting based on a photo they took. Tlak about how
artists use photos as references.
I'm just thinking at the keyboard--I don't know if any of these ideas will
appeal to you, but perhaps something will spark an idea you can use.