In reality, I'm thankful you're "kind of nervous" over your new responsibility! If you weren't, you'd probably go into it relying solely on your own wisdom, instead of turning to God and seeking His help.
But that's exactly what you and your colleagues need to do: Turn to God and seek His help in everything. After all, this isn't simply the work of your church; it's God's work -- and because it is, He knows what is best. Even when you're dealing with very ordinary-sounding things (like finances or whether or not the building needs a new roof), you still need God's wisdom, and I hope you will seek it (both privately and as a group). The Bible says, "Trust in the Lord with all your heart and lean not on your own understanding" (Proverbs 3:5).
In addition, as you have opportunity I hope you'll encourage your colleagues to think prayerfully about the future. Perhaps the most important question they can ask is this: What does God want to do through our church? What are His priorities? What new doors does He want to open for our ministry? How can we reach others for Christ?
Finally, on a personal level, ask God to help you be a Christ-like example to others. They'll be watching you in ways they may not have done before; will they see Christ in you? The Bible says, "In everything set them an example by doing what is good" (Titus 2:7).