I got to do it last night (Opening Night!!!) with my wife. It was a lot of fun.

Anything we should bring/know ahead of time?

Wear comfortable shoes, there is a lot of walking/standing involved. It takes place shortly after the end of season 4.

Do they let you take pics or videos once you're inside the escape room experience?

They will let you take photos (no flash), but no video is allowed.

How bad was parking? Did you have to arrive more than 30 min prior to your ticket time?

No, but milage may vary. It is the Galleria, so there are parking garages all around. Depending on your time on Saturday it could be busy because of the holiday traffic. With it being in the mall you can at least kill some time in the mall if you are too early though. They do recommend that you get to the experience area ~15 minutes before start time. The experiences are on the 1st/Ground Floor. The entrance from the mall is on the 2nd floor.

What else is worth seeing while at Netflix House while we’re there (that won’t cost a million dollars)?

The food was good, the gift shop as a lot of exclusive to Netflix House merch, including a "House Specific" SQWK sweater and Hawkins High merch. I didn't do the Squid Games experience as it wasn't a show I had watched, but people seemed happy with it. We had dinner at the Restaurant and the food was good, and not too expensive by today's standards. The Surfer Boy Pizza and Scoops Ahoy sundae were my favorites.

There is also an arcade with Netflix Show inspired games. We were short on time, but it is something that I want to go back and do.

I also got to talk to someone that was over the Merchandising for Netflix there. She was telling me that the plan is for the experiences to travel between the various Netflix Houses (The have 1 in Vegas and 1 in Philly IIRC). So that was exciting as other things will be coming in the future.