Thanks! Answered all my questions perfectly.

New house, I figured I need a new filter for my furnace for the change in seasons and went into the utility room to find the size I need. When I opened the filter drawer, the airflow on the filter installed was pointing left. Here is a picture of the furnace. Shouldn't the filter arrow be pointing to the right instead?

Also, and this is likely an equally dumb question, I have no idea where the filter for my AC unit is located. Is it possible the filter for the furnace also filters the air from my AC unit outside?