Letting dry on the balcony will do, especially if its in the sun. The aim is to disinfect, not just clean.

I just hose mine off, use household disinfectant as per instructions and rinse off. If I'm in a rush I'll dry with a rag but leave it out in the sun if i can.

Regarding litterboxes, I have heard metal is easier to keep clean as the plastic ones will get scratches, which will harbour the bacteria. Personally haven't had any issues yet as long as I clean it properly, and it's also not easy to find in stores except online. So what you get will do just fine.