One of the main problems I'm anticipating with character and backstory integration in such a large, sparse world is what it means to be familiar with the world. You're all starting in Mountport, and yet you are free to be 'just visiting' for the first time and have acquired decades (in some cases, centuries in others) of life experience elsewhere. You should feel free to know quite a lot of people for what's in your backstory. Please (!!!) go crazy with that. But I don't want you to feel stuck as the campaign and the party's own needs and wants have you in new and unfamiliar places week after week.
I have decided to adopt what I hope will be a useful framework to fix this, an 'I Know A Guy' house rule. The basic idea is that you will be free to interject wherever and whenever with your own claim to 'know a guy' that might be useful to know in whatever situation. Maybe the party is stuck, or maybe you're craving some extra rp time. Maybe you just wanna see the DM panic to improvise something completely unexpected. I do hope you'll end up having enough fun to be motivated to bully me a little bit with unexpected nonsense in my sessions.
When you decide to invoke the 'I Know A Guy' rule, the game will temporarily pause as we figure out who it is. It's your call if we use a private channel to negotiate or use session voice.
While everything about my world is potentially up for debate, at this current time I am planning to give every player two uses of this rule. Spend them in literally any manner you like.
And, one more little note. There is no policy in place that one usage is good for exactly one person. If for some reason the party needs to gather a small crowd and you want to 'I Know A Guy' some old family friends or neighbors that moved away and just-so-happen to have settled nearby to help with that, I am open.