CONGRATULATIONS!
Yeah, it's great and scary at the same time. And they do turn into teenagers, but 9at least in my experience) they eventually turn into human beings again. Now that mine are older (like 32 and 28) I can say the best advice ever comes from the words of Hoddng Carter. "There are only two lasting bequests we can give our children. One is roots, the other, wings." Work to do both of those in equal measure, and you'll be succesful.
Balance? That's the tough part. First, don't neglect your marriage! Well after the kids are gone, you'll still have their mother and from bitter experience I'll tell you that you HAVE to keep focusing on that relationship. And from my own experience, I'll say I missed too many birtday parties, trips to the zoo, reading bed-time stories, talking about women, etc. in order to play gigs.
But the plus side is that my older son (who's a GREAT father with an 18 month old son) is a theater tech. He knew that a life in the arts was a rough gig and he knew that's what he wanted anyway. I've been rewarded by seeing him learn from my mistakes and be a better balancer than I was. My younger son asked me a few months ago about playing bass. I sent him one of mine (he's in Oregon so I haven't seen him in a year), and some tips on getting started.
Both boys love music, and have become very opinionated but articulate critics. They have wide tastes (Geoff had a mix tape that ranged from Pachabell's Canon to P-Funk, Sean had radio show in college where he played a lot of my albums). And one of the funniest moments was the day Geoff came home one day in April and said "Do you know how cool it is to drive around with all the windows rolled down, cranking "Purple Haze" as loud as you can?" "Oh, yeah, YOU do!".
So, in summary- to be a great father you need to love their mother and them unconditionally. Trust your instincts. Spend time with them giving them your undivided attention. Talk WITH them. And have fun with them.
John