1. The Android clipboard prefers Ctrl+C while Mac uses Cmd+C. When you highlight text in Pleco aka the AVD, you can also click Copy in the tooltip manually. However, to speed that up, I used a program called Karabiner to map Cmd+C to Ctrl+C only for the Android emulator. So, now it's quite smooth to move between the two OS's.
2. Yes, you could run multiple virtual devices with Pleco if you wanted, although not sure why.
I attached some example images. The first shows the interface, I've highlighted external text in a web browser and you can see the paste tooltip within Pleco recognizing new Clipboard, you could click it. The second is showing a paste and clipboard sharing. The third is highlighting text within Pleco and either Ctrl+V or clicking tooltips will work to leave the AVD.