The passageway you speak is not needed for your app. It is the choke stove passageway and can be plugged.
Not sure of your car application but on tbirds the intakes were fastened with a flat washer under each nut or bolt, no lock washers. The torque specs are 23-28lbs, center to ends.
I only use sealer, rtv/red at the front both sides of the gasket material around the water jacket opening, sometimes a light coating of grease on the rest of the gasket.
Try to check to see if you have good alignment/angle first with your existing heads, by sighting down the length of the head in case the manifold or the heads have been perviously milled at one time. This is an area for potential vacuum or water leaks, but usually I have found it to be pretty forgiving.
Just an additional thought. while you're at it you may want to block or constrict the heat riser passageway in the gasket if you don't have the restricted type gaskets to prevent the paint on the intake from burning off. You don't need them as much since you have an electric choke, unless you are in unusually cold climate.
If you do a search on here there is a discussion about that topic.
A L A N F R A K E S ~ Tulsa, OK