Specifically I'd like to be able to set/change the maximum amount of space they take up, alter their size in terms of pixels, left-click through our (de)buff icons as well as right-click through all others, and do so with pet, party member (when raid frames aren't up since some people still don't believe in using them), and target of target (de)buff boxes.

Seriously. Buffs and debuffs take up an absolutely insane amount of space and can sometimes make it difficult to nearly impossible to left-click for target selection during those many, many times when "tab targetting" is a recipe for failure.

Yes, I'm aware that you can reduce the number of (de)buffs displayed on the various unit frames within the Interface settings section, but that's not exactly a fix for not being able to resize the buff boxes, set permanent limits on how big they can get, modify the size of the actual icons, or just plain click through the damn things.