If you’re on Mac, go to the Apple Logo in the menubar, and click “About This Mac…”

64bit apps and OSes are more complex and can utilise more RAM. I think Catalina was when macOS fully committed to 64bit architecture and left 32bit behind. So, if you’re running Premiere CC in that OS or newer, you should be fine.

The bitrate of the video shouldn’t matter based on the codec settings you listed.

In the About This Mac, you can also find info about your graphics card. Intel Iris graphics and other Intel graphics cards are integrated to the CPU and share their RAM. If you have an NVIDIA or AMD graphics card, it should have its own dedicated RAM.

Also, in Premiere Pro’s preferences, you can dictate how much RAM the application has access to. This is to keep the application from choking your system during an export, but the default may be lower than you want. I’d set it to 18GB or 20GB, that way there’s 4-6GB RAM for any other tasks you’re doing.

I’m using a late-2014 15” MacBook Pro (I’d have to look up more detailed specs), and I don’t seem to be having that extensive of export times unless I’m doing a lot of graphics-intensive work, like color correction or VFX.