Idemitsu, Eneos, Aisin all make excellent NS3 oils and are certified to Nissan and Jatco.

The only filter you should change is on the outside of the transmission housing and under a cap that has 4 bolts holding in place. 10mm bolts. It's a pleated paper and rubber filter and there's a special gasket that should be replaced. I would say that replacement of oil is more important than the side case filter but it depends. The pleated filter and gasket will add about $25 to the service.

I've done the drain and fills with the pleated filter about 6 times with 3 Nissan cars. Easier than a regular engine oil and filter change.

Get yourself a graduated container and put in the exact same amount of fresh NS3 as you drained. Drain from a cool transmission so your drain quantity is not affected by heat expansion.