"You've just moved into town and you wanna know the big players. Fair. There's the basic info you're going to get from your usual methods - you're shadowrunners, this is part of the job. BUT - tell me a) how long do you want to spend researching, b) how low of a profile do you want to keep in this, c) how much are you willing to spend? Detailed, fast, quiet, cheap - pick 2."
The trick to good info management isn't withholding information from the players, it's about figuring out what methods and prices they have to pay along the way to get what they want and building the adventure from that.
Are they doing things discreetly? Or are they leaving trails? Will some groups tag them as trouble makers, potential rivals, or good suckers to throw in on a bad job?
Are they pissing people off along the way? Making enemies in a town where they've got few allies?
Are they throwing around a lot of money? Are small time runners looking to jack them? Are big time players suspecting they're just a front for a rival corporation/group?
Are they asking "too many" questions about a particular group and word is getting back?
It's not just the price you pay in time and effort, it's also what the rest of the world thinks of that, and the actions everyone takes in response.
Mechanically - it's as easy as a dice roll. Fictionally, as a Shadowrunner, you're stepping into someone else's mess and maybe you want to step carefully.
As far as playing it out and not writing massive setting stuff, ask the players in return - "What are you looking for? Are you looking for employers? Marks to hack/rob?" and target your answers around that. For some details, on a successful roll, you can turn the question back on them - "Well, 'Uncle Knife' still runs the docks, which is damn impressive in day and age, but he did something that has caused all of his rivals to back off - you only figured it out when you looked at a shipment record from something 2 weeks ago. What was it?"