Sealing Chimney Liner Joints

I know that EK wants all liner joints sealed (I'm not sure how critical this is), and though the installer I'm speaking to doesn't normally do that it appears to be an option.

I see three joints: where the horizontal snout meets the vertical tee, where the tee meets the (20' 1-piece) flexible liner, and where the cap goes on the drop leg.

I was told that the tee that he uses is male at the top and inserts inside the liner: every tee I've seen had a female connector at top, which would seem to validate the need for a sealant. Are there tees that are male on top, and even if so, is sealant required?

I was also told that the drop-leg is only about 1 1/2" long and his intention is to leave the cleanout area below the tee sealed and we simply won't use it. If I'm correct, when cleaning the liner you would always disconnect the appliance and it's being suggested that one could vacuum out the tee and the drop leg through the snout: is this reasonable? Is it still reasonable if the drop-leg is 4-6" which they normally appear to be? If so, would one seal the cap in place?

If this is not the way to do it, I assume you'd need to extend the drop-leg down into the chamber and then cap it, and you'd have to remove/replace the silicone every time you get the liner cleaned?

Lastly, for the EK1, how far out from the wall should the horizontal snout come?

Sorry if I'm putting too much thought into this, and thanks for your help.