Restricting air flow by adding a filter actually decreases the load on the fan motor in direct relationship with the reduction of air flow. If the air is restricted too much, the air cooled motor may overheat.
MERV Rating (Minimum Efficiency Reporting Value)
It is heavy fabric, maybe 1/8" or so.
I have not put this in my washer but I think it could go in a washer that doesn't have an agitator. I'd recommend washing it alone or with other similar items as mine catches a large amount of sawdust. Also, I don't think it should go into the drier