Hmm, might help if I explain how this process can work. A good example is the star system Luca, described in Core. The planet onto which the gates open, Luca II, is in the terrestrial sweet spot where earth-like planets can arise, but the system has one major fault if you're a life-form: it only has one gas giant, and no ice giants. Giant planets help shield other planets within their orbits from asteroid impacts, so Luca, with little such protection, has a dusty atmosphere and a heavily cratered surface from constant bombardment. It's colder than it should be for where it is relative to its star, thanks to the nuclear winter-like effects of bombardment. It's older than Earth, so like Mars, it doesn't have much tectonic activity and has experienced little resurfacing in the last few billion years, leading to a lot of low, broken hills and cratered plains. With few mountains to break up storms, the weather is decidedly crappy.

So what kind of life do you get on a planet like this? Much of it might be subterranean, or at least burrowing. The planet's only sentients evolved from insect mound predators, then died out. What's described of them follows from their environment: they had infrared vision, and their civilization never really took off. Sadly, they were doomed by their unfortunate celestial position. A major asteroid impact ultimately did them in.

Luca II is one of the less exotic exoplanets, but hopefully this illustrates the process well: start with science, make some predictions, and then twist them around until they're sufficiently interesting.

There is mention of Xenosystem Gates just floating in space (I cannot find it now, but it is somewhere), so yes I imagine there are ones that go to places in the middle of nowhere. Hell, there might be ones that are literally in the middle of nowhere. Now think how useful such a location could be do a Corporate Entity. A point in the galaxy that only has one entry point. The only way in is through the space gate, unless you have FTL tech.

And I am almost certain that gates exist on both sides of the connection, much like Stargates do. In fact they work almost exactly like Stargates do. You dial in a connection address, walk through and you emerge in an instant (The fluff says an instant, but sometimes that instant can seem to last like an eternity) on the other side. Special magic stuff makes it so atmosphere does not transfer, just like a gate. I wonder what happens when you fire a gun through one. Or a laser.

http://direpress.bin.sh/tools/system.cgi

This will generate a solar system for you.