It builds (automatically and free of charge) little freighters that fly to metal and crystal extractors, boosting their output and thus giving you a little extra resources. Check the metal and crystal numbers in the top right (hover over it for a bit) to see how much you get from it atm.



Research the corresponding upgrades from the civilian research tree or build a refinery nearby.



Yes.

If it was your homeplanet, you have to set up a new homeplanet asap or all planets will lower allegiance to 25% (resp. 35% if it has culture). Also if the enemy has broadcast centers and you don't, quickly build up one of yourself or you'll lose allegiance pretty fast.

It's important to build broadcast centers at or near your further-out planets too. Planets that are two or more hops away from your home planet have a maximum allegiance without them - 90% next door, 80% two hops away, and so on. So if you have a high-resource planet that's four hops away, you're only getting something like 50% of the resources and taxes that it could normally provide because you're so far away from your homeworld.

Note that allegiance climbs without a broadcast centre in the gravity well if there's one in a nearby gravwell that has had its culture spread to that planet - but this can take a while.

-- Retro