For insurance, one of the guys that helps us has event insurance for his car club. Thats what we use.
Talk with several agents about it and find the best prices, I just found another at half the cost if we need to get insurance. Make sure they know its event insurance and a racing event.
As far as the church parking lot, make sure their insurance doesn't have any stipulations above and beyond the event insurance. The church elders may also have requirements.
We are going to be running once a month come next spring.
your first step should be contacting local clubs,a little help goes a long way and they may also give you some ideas. The scca would also be a good starting point.