1) I take off my roof panel whenever the weather is at least 70 degrees and I'll be driving for at least 30 minutes. In other words, most of the time I drive my NSX (I love L.A...or, should I say, living in L.A. near the beach).
Actually, I haven't taken off my roof panel during most of our canyon drives because I've had bad experiences when doing so (too hot under the direct sun, too cool and breezy under the marine layer). And I probably won't take off the roof whenever I shoot in-car video.
Also, it's best not to get caught in The Valley with the top off...I've been stuck in traffic on the 101 in 90+ degree weather (why I didn't take the coastal route was beyond me).
2) I've never put it in the trunk (and don't see any reason too since I don't mind keeping my engine covered)