Hey Matt - I'm just another player but I figured I'd post a quick reply until John or someone else can post more info.
Whatever character ideas you have, I'm sure they'll work. Read the rules twice and when you're done, read 'em one more time. If you're familiar with how most LARPs are set up then you'll understand what sorts of things you'll need to keep in mind when creating a character: namely you're a starting character with almost no equipment and no street cred. If you've specific ideas and questions about the rules, might want to to post them over in the rules section (I think we've got one of those...)
As for what to bring (equipment & weapons), bring whatever you want. You might be a little limited at first in what you can
use IG but if you bring it, you'll at least have the prop for it. My first SAGA event, I crono all of my weapons (5 I think?) but could only start with one. However, when we found a shotgun later, I was ready with my extra prop.
As for ammo, I'm not sure if John is going to be changing the ratio but last time I played (granted I was only using a pistol and shotgun), I think I used less than 200 rounds for the entire day. You will be limited IG by what you're able to find. So, you likely won't be spending much time rolling on full auto much. Only when a boss shows up or most of your group goes down. Yeah, you'll spend a
lot of time IG worrying about ammo and where you're going to find your next set of reloads

As for events, I believe John is in the process of setting up weekends and locations. When that would be posted, don't know. Off-handedly, I wouldn't mind trying to run something soon. The weather is finally nice enough, it's just a matter of getting things in place.
PS - what's your general location relative to Pittsburgh?