You've got a great kit too Jim. Some things I'd like to have.
As for you questions:
Suction devices are pricey. I used a turkey baster in the past, and might get one again. The Rescue Vac retails for something like $100, and doesn't actually fit into a mouth too well. But it is a shortcoming.
The 2 C-collars are adjustable. Sectionable's aren't used too much in the field (in my experience) in the US. Mainly hospitals. Plus, they don't fold or store as well.
A BVM adds 5% more O2 than a face mask when in use (21% atmospheric oxygen, vs about 15% in an exhaled breath). Plus, it keeps your head away from the patient while in use. The last time I used one on the side of the road, the girl's head was smashed and blood was spraying everywhere with each breath. I'd rather my jeans be soaked than my face and hair. The nice thing too is I can hook it up to an O2 tank when one becomes available (cops sometimes carry them, and tend to be quicker than EMS at times)
No cuff simply because I'm not cared about documenting vitals. If they're talking and have a radial pulse, their BP is at least 70-80 mm Hg. This kit is to keep alive, not titrate IV fluid rates. Besides, without an IV, I can't do much to improve a dropping BP besides more hemorrhage control. Lastly, blood pressures aren't part of the triage algorithm, and if there's more than 1 patient, I can't waste time getting full vitals on each one.