Some questions about bees

OK, I think that I have correctly identified some bees, at the very least to tribe, but I'd like some behaviour & location information, please. I'm in Burnaby, BC, Canada (west coast, urban environment), with a really diverse garden that we tend not to dead-head so that seeds will be produced and don't do a lot of physical cultivation over much of the area, so I know we get ground-nesting bees.

Chelostomoides: are these really tiny? Like maybe 5 mm or so lengthwise? And do they move around a lot between flowers, rather than sitting in just one spot for any length of time? I have what appears to be them all over my mint-family herbs right now, especially the small flowered things like the oregano, marjoram and lemon balm. I cannot get a good photo; none of them will sit still long enough. They seem to be pretty aggressive towards each other, too.

Anthidium: I think what I'm seeing are the males; they're extremely active, moving very quickly scouting from flower patch to flower patch, and will zoom in on another bee (not sure if it's the same genus/species) really quickly & out again. I cannot get a good photo, they definitely don't sit still at all, at least not in my back yard. This one looks really similar to what I'm seeing, but our seems to have more black area on the abdomen, I think more like this one, but I'm not 100% positive. Does my description fit their behaviour? These are really robust insects, built similarly to a small bumble bee, but no where near as fuzzy.

I have some more, but I'm going to try posting to the ID section; they're pretty crappy photos, but I'll see what I can get!

Thanks everyone!!!