Rough-legged Hawks have "belly bands" as well but theirs are more solid rather than streaked. Also, light morph Roughies tend to have lighter-colored heads and smaller beaks than Red-taileds.
Juveniles tend to be darker than the adults.
http://www.backyardwilderness.net/wordpress/wp-content/uploads/2011/06/2011_06_21-120W.jpg
http://www.nejohnston.org/birds/2013/09/Images/IMG_3643.jpg
I am pretty confident. The 4th photo (of the face) especially looks like a Pine Warbler. Yellow-throated Vireos not only have larger bills, they have larger eyes and a more contrasting face pattern. Your bird also appears to have orange feet which rules out vireos (which have blue feet).
I can't really say how many we see on average. We see a lot more raptors during the spring, fall, and winter months. In the summer we maybe see one raptor (mainly Red-tailed, Broad-winged, or Cooper's) every other day.
#2 is a Lincoln's Sparrow (gray base color on face, buffy malar, thin streaking on buffy breast and flanks, raised crest). I'll let others ID the first since I have no experience with Brewer's.