Benefit to multiple interceptors on one satellite

A few hours into the game, I can't answer the biggest part of the question ("What is Captive [Alien] good for after associated interrogation is done?") except to say that you can't sell them, so I suspect they must serve some purpose down the road, however menial.

However, I've noticed that in the case of Sectoids, for instance, I often get an undamaged Plasma Pistol along with my captive, instead of generic weapon fragments.

Seems like there are pros and cons to capturing instead of killing aliens after the first of each type.

Pros:

• You do get the captive, which might be useful later.
• You acquire the enemy's weapons in one piece (dead enemies yield fragments). You'll still need to research tech you haven't yet (laser, plasma, etc.), but it often let's you get at better/more expensive stuff than you otherwise could.

Cons:

• You don't seem to get the experience for the kill.
• It's often harder (obviously).

It is in fact an event where you will get a chance to get more resources. This is really important; you need to acquire certain materials to do certain research to get a path to victory in the game, and that says nothing of getting your soldiers properly outfitted.

As to the randomness, that's not likely. The aliens have an agenda and it will play out on the geoscape. UFOs have missions; shooting them down prevents them from carrying those missions out. Allowing the aliens to carry out those missions will help spread panic/alien presence (at a high level) which is bad for you.

I have only ever seen ufos where I had satellites deployed. Eventually you will need to upgrade interceptors as they will start encountering much larger, more powerful craft.