Running nitrogen

So today i got my regulator in and i will have my bottle brackets by next week so my question is, if I should run an expansion tank or is that not necessary with nitrogen. I also want to know what line you are using to connect your regulator to your tank. My regulator came with a hvac purging hose that has a flared female fitting on both ends so should i use a flare to npt adaptor or get a new hose thats all npt?