[Scott]

The car takes just over 5 quarts. 5 should be sufficient, but check the dipstick after changing the oil to see if you need a touch more.

You don't need a new gasket on the new filter. What you DO need to do is take some of the drained oil, and "wet", or lubricate the outer rubber seal on the new filter before putting it on.

You don't need an OEM Honda filter. K&N makes an oil filter that works great.

You should be using 10w30 synthetic oil. I personally prefer Amsoil, but it's a bit more pricey than regular synthetics. Mobil 1 should be just fine.