Thermostat neck from Billet Technologies

I have a small leak around the bottom of the the thermostat neck on my 440 Dart. I know this is a common problem. I had the motor rebuilt over the winter last year and the new manifold is an Edelbrock performer series aluminum manifold. I am going to try the Billet technologies aluminum t-neck with the rubber o ring seal as I have seen it recommended here and there.

Questions I have are as follows.

1. Since no gasket is needed with this do I still use RtF anywhere?

2. Do I use silicon or some other sealant on the bolt threads?