I'll start with a caveat that it's been a few years for me since I've had to bother with that lot.
The northern part of the movie theater parking lot is open to commuters. You'll notice that the lines are a different color from the rest of the lot. I can't speak to enforcement after 6:45pm. There are a few times that I've stayed past that time, but didn't have an issue. I've never seen chalk marks or anything on my tires to indicate that I was being tracked.
As far as towing in non-commuter areas of the theater parking lot, it seems to go off and on. As people get more brazen and start parking closer to the theater, they start cracking down. One time I received a warning leaflet that my license plate had been recorded and would be towed if caught again. I'd also see tow trucks in process of towing vehicles. I chose not to try my luck again.
I've parked on the edge of the Stop & Shop parking lot, right next to Kingsland and didn't have a problem. Of course, this is a bit of a hike if you're taking the express bus. It's a little bit of an easier walk if you park on the east end of Stop & Shop and walk along the delivery road that runs behind it. I also see people parking at Target to take the local bus but have never done so myself.
I've never bothered parking near Barnes & Nobles because I assumed that's the first place they'd look to crack down on commuters, but don't have any info one way or the other.
Personally, I recommend buying monthly train pass from Delawanna. It costs slightly more but Clifton Common buses will honor that pass and you have the flexibility of taking the train. Worst case situation if there isn't any parking (or hear of severe traffic), you have the option of taking the train at Lyndhurst where there's always parking (Delawanna parking fills up just after 7:00am). During the winter, the trains will run far more smoothly compared to the buses. Just be careful about taking the bus home to Clifton Commons and then remembering that you took the train in the morning and have your car parked at Lyndhurst. Don't ask me how I know about that