The tweeter is attached to the grill cover. The only opening in the grill is where the tweeter is mounted - a larger diameter tweeter will be partially blocked by the solid part of the cover.
In another thread hop23 referenced a wiring diagram and stated that the door and dash speakers were in parallel(?). But we know they are all 4 ohms, so I'm not yet sure how the stock amp handles this load. I still have the same question about after market cross-overs (as part of a component set).
Yes, the dash tweeters are in parallel with the FRont door speakers. That makes a 2ohm load for the FRont speakers, and 4ohms for the ReaR speakers. The rear woofer is on its own channel.