How long should I keep the pop-up open after rain?

I've never had to close up mine in the rain, but if there has been moisture due to morning dew/humidity, I pop it up for a few hours at home just so everything has a chance to dry out. I also keep a couple of buckets of "Damp Rid" inside at all times - you can get at WallyWorld. This helps keep inside drier and less chance of mold/mildew.

Hard to say. We leave ours open for several days then run a dehumidifier. Mold & mildew ruin alot of HTT & pop ups.If you felt everywhere, especially windows & low spots, you might be Okay

It's really hard to tell. Any moisture trapped inside a closed pop-up has potential for mold growth. Depending upon the outside humidity, air movement, and the temperature, a surface may appear to be dry, but can still have wet moist spots. Threaded seams can still be moist when the rest of the material is dry. And then again, it might have dried out completely.

You really won't know until you open it back up.

When we had our pup, it seems we ALWAYS had to close-up shop in the rain! After 6 years we reached the breaking point and decided to get a hard-sided trailer. But ... we were also fortunate to be able to park the camper at home, and I could pull the camper in the garage, corner-to-corner, and raise it about 4 feet, enough to let the side hang down and dry out. Sometimes it took a week to really dry!

Also... we slept many nights in the camper, half raised up ... in the garage too! (Boy, those were the days!)

I think you're good. How long will it be in storage until your next adventure ?