We are not quite sure what the dogwood insects are. They appear to be stinkbug nymphs. If we get a better answer I will let you know. If you see the adult version of this bug, please send another picture. Some stinkbugs are beneficial insects, but most are pests. I would shake them off into a bucket of soapy water.  

The rose insect sounds like the dreaded Japanes beetle. Please see the following for identification: http://www.extension.umn.edu/garden/insects/find/japanese-beetles/

Thank you.  I think you are correct about the stinkbug.  It looks like a tiny version of the Brown Marmorated Stink Bug, with banding on the abdomen.  They just appeared this week after my dwarf redtwig dogwoods, which were mostly dead this spring, were cut back and putting on new growth.  New foliage never did look healthy however due to 'mites' on the underside.  No idea where the bugs came from or where they overwintered.  Should I take any precautions regarding other nearby plants?

Whoops... the red bug is not Japanese beetle.  It's very slender, with a scarlet red body and shorter black wings.  Will try to get a photo.

Definitely keep an eye on the other plants and try to kill a many bugs as possible. If they are stinkbugs, crushing is not recommended as, well, they stink. But it feels really good...