987 Newbie Questions

[RoadHazard]

Just bought a nice secondhand 2005 Boxster S. It's my second Boxster, but my first 987, and it's just different enough that I'm scratching my head over a few things.

1. What's the black box inside the front trunk upper compartment where the CD changer and/or navigation system would go if I had them?

2. The center air intake in the front bumper isn't actually an air intake. It's closed. Also, mine's loose and wiggles. Is there a clever way to snap or screw it into place?

3. The car came with a loose piece of black plastic, part # 987.561.446.00. PelicanParts stocks them but doesn't describe what it is if you don't already know. Where does this thing go?

4. The soft top appears to be in great shape, but it doesn't seal properly when it's closed and I get a lot of wind noise (but no water leaks) at highway speed. It looks to me like the edge of the fabric top isn't sliding into the plastic guides (where the B pillar would be on a hardtop). Is there a way to adjust and/or train the top to go into these grooves?

5. Programming the HomeLink buttons is a constant source of irritation for everyone, but a bit of searching suggests that my 2005 car won't ever talk to my 2014-era garage door opener unless I get a "HomeLink repeater/bridge" gadget. Does that sound about right?

6. Confirm, please, that I can disconnect the battery temporarily without borking the radio and needing a code to re-enable it?

7. I've been reading horror stories about using the wrong coolant. I've got a bottle of Peak European Vehicle Pink coolant that says that it's good for 1996-2009 Porsches. Surely that's okay for the occasional top-up?

Thanks, all!