Installing compression fittings for PE gas pipe

I am installing some PE gas pipe for propane service and have some compreeion fittings to connect the poly to balck pipe and need to know if ther is any special tricks to installation. I am running about 130 feet of 3/4" poly from the tank to the house and then back underground to a fireplace and a spa heater. The fittings themselves look pretty simple. A one piece Powder coated 3/4" iron nipple with a larger diameter bell and a barbed interior that fits inside the PE that a large neoprene/ metal conical washer fits over and then a large nut. It seems just like a regular compression fiitting to me but I haven't tightened them up yet. Is there any special preparation or sealant that should be used.

Moving along slowly but another question

Just tightened one fitting onto the end of the PE. Seemed to work fine? I am planning on putting another Compression fitting on the end of the PE pipe roll and capping one end off so I can put my pressure gage rig on and test check before putting it into the ground. Question is Can I take one of the fittings off and use again after I cut my pipe to length. Also should I cut the PE back from the end of the roll or is the mfg's end OK? Balck pipe is one thing but this is PE is new to me. THANKS IN ADVANCE

Fred