For context, this takes place about 300 years in the future. The space city in question is located in a nebula, completely man-made (not build upon any preexisting foundations like an asteroid etc.), densely populated and continually expanding, and possesses a surrounding force-field in order to create a habitable environment within. It is isolated from the control of any sole government and is established as a hub for interplanetary diplomacy. Thus, it needs to be mostly or completely self sufficient, but does receive shipments of outside goods.
What I would like to know is:
would drawing and converting power from developing stars within the nebula be a feasible way to power the city
are there any dangers presented by this location either to the city or the ships traveling back and forth
what steps could be taken to minimize or protect against such dangers