If I wanted to sell something to someone I don’t know like on Craigslist can i do it in front of the station

As long as you're in a public sidewalk, you have the right to do a bunch of stuff (e.g. recording people around you, hanging out with your friends, eating your lunch, drinking non-alcoholic beverage, etc). As long as it is not illegal, they should have no problem with you minding your own business. Note that police's duty is to serve the public. One should never be afraid of cops. They are here to serve (legally speaking).

Yes