Yes, it is highly likely the work of Powderpost beetles. If you find small holes on the wall then it's already a sign that your wall has been infested. It's a good solution to call for pest control right away.
I'd suggest that you install air grilles if you're concerned about the air flowing from your ac. It maintains the circulation inside your garage office by sending out the conditioned air outside and drawing in fresh air. It's also not a great idea to add an exhaust fan in the wall since it would...
You can also move the router to the center of the house. If the problem still isn't resolved, update the router to a newer model or have a wifi extender installed in your house. Hope this helps out a bit.
You can also have them collected at a local recycling center if you want to minimize your carbon footprint but I like your idea about using the cardboard boxes as bedroom trash cans and liners for the bathroom.