im not reading ALL of that, so if i missed something i apologize...

since it doesnt rattle at a light, i would imagine it wouldnt be a vacuum problem, but it _could be_

your idle is higher when oyu first start your car, thats normal, thats what a car's engine is designed to do...sort of like a choke, (in fact, i think it _is_ a choke in a way, but now theyre automatic), after your engine achieves a warmer state the idle will slow down, and Honda engines at idle are barely running. you could check the slack on your accelerator, and you could proly turn the idle up if it really bothers you.