Did the WMII/DWM guys (last time I read the mailing list they were in the middle of a holy war, something to do with the websites I think, but that was a while ago) ever add the ability to change the tile size without the mouse?
DWM only has title is in its status line, do you mean status line font size or something else? DWM does not have title bars.
Edit: Ouch, too early. You are asking about tile and I read title. Ok, tile size is managed by keyboard shortcuts in DWM, don't know about WMII.
Also, can urxvt set transparency to each individual color (ie. black is transparent but white is not)?
No, I don't think so. You can only set transparency for terminal background color. This is what I have in my .Xdefaults:
urxvt.transparent: true
urxvt.tintColor: black
urxvt.shading: 80
urxvt.fading: 20
You can set any color to be used for shading math but that works as replace background color with tint color and apply shading to wallpaper. Shading=80 is 80% transparency. Fading is applied to non-focused terminals, they additionally fade with the background and that helps to spot focused terminal immediately.
Urxvt also has good xft font handling and you can set almost anything, here is my font line:
URxvt.font: xft:Monospace:pixelsize=12:antialias=true:hinting=true