Hot-End Nozzle

I have some concerns about tightening the nozzle, I have a suspicion that my nozzle will ‘bottom out’ or run out of thread before it actually clamps.
Is the seal accomplished by the threads, the same way plumbing is with the aid of tape of course.
OR
The male threaded part (specifically the portion at the end where there is no thread) being driven into the mating part of the nozzle.
I hope I have explained this properly.

Is there any type of sealant that can be used to improve this step. (ie: ptfe tape)

And finally the crinkle washer/bell washer. Is its function to help prevent over tightening or is it to provide a spring force between the two surfaces to achieve the seal ?

Ive recently just assembled the hot-end.
Using a small torque wrench tighted it all up to the recommened torque.
But one small thing still bugs me and I thought it best to ask the question as I hav’nt heated it up yet or feed filament through it as I’d like to know whether it is a probelm or not.
I have a small gap (0.1mm to be exact) between the heater block and the nozzle.
Will this be a probelm ?, ie: restrict heat transfer
I believe the threaded part has reached the bottom of the nozzle hole before the two surfaces have come into contact.

Am I safe just to leave this or should I take it apart and place an apprioate shim in-between to fill in this gap. ?

There should be a spring washer that you mounted in that area.

I have fitted that washer as per page 14 on the upper section of heater block. If that we’re missing I’d have a massive gap and heater block would move up and down.
Mine does not move up and down

I guess I’m not following what you are talking about.
Could you post a picture?