Let me differentiate a bit.
The crankcase connection goes to the nipple on the cast carb cover nipple
The free air vent line goes to the sheet metal carb cover nipple.
Neither of these should rotate freely.

On running in:
Rather than write a complete book on gas engines here, have a look at the very complete [link=http://www.3w-modellmotoren.com/mounting_tips/manuals_engl/50i_engl.pdf]3W manual [/link] which is very informative, and also covers many other things so important to the beginning gas guru.