Thanx for the feedback.

The negatives were scanned by the lab that processed them.
There are worse pictures (mostly worse composition and lots of magenta)... I picked the better ones that illustrated my issues with focus.
I had focused on the pipe a bit above the middle, where the light made it easier. Then I apparently moved, so the air is probably nicely focused somewhere
When I take a slow hand-held exposure, I focus first, then take a stance I know I can hold. Motion blur and mirror slap are different issues that I can identify and know how to deal with.

Looking back, I don't think the focusing screen is my issue (though will look into getting another to make life easier). I think my main problem is shifting my posture (even slightly) combined with not realizing how shallow the lens DOF is compared to 35mm. These will be tough as they involve a life-time of habits more than anything else.