1. Does the owner of a city receive any income from that city?
2. Does the owner of a city need to own facilities in the city to receive city income?
Couldn't find anything in the rules regarding city income. If the answer to the above is no, then what benefit is there to buying a populated city off the market?
The point to purchase city slabs is so you build facilities, to get the income. If you own all the buildings in the city slab, you have to have one building that produces income. So not from the city, but the facilities within.
Many of the cities on the NPC market are only about 17% filled, .. lots of space to build. Also, buying a city, putting flats on it, if you are a faction, you then take over the planet, and no one could build there except you. Another perk if you own a faction and want 'cheap' control.