Re: EF Speaker dimensions
I have a set of Alpine splits in my EF. I'm not sure what the mounting depth is, but they don't foul the window, and didn't require any modification.
With the tweeters, I just stuck them up on the little bit of plastic near the power window knob (I can take a pic if you need). All that was required to fit them there was I had to drill a hole through it to feed the cable.
I'm not 100% sure about the JVC, but you should be able to hook up a stacker to it. I don't know if they make an MP3 stacker though. If you hook up a regular stacker to an MP3 head unit, you'll only get MP3 capability at the head unit. JVC might make an MP3 stacker (check their website) but I know Alpine and Pioneer do.