The router its self is .1, though I have DHCP set to start at .1. I assume the router is smart enough not to lease that address out to another computer, right?
Possibly, but it certainly
isn't smart enough to avoid your other static IPs at .2 to .9. Set it to start at .10.
The subnet mask is .224. I can't remember why I set it that way. I think it was because the incoming internet connection (which is static IP), has a .224 subnet mask, but it's not a requirement that they match, is it?
No, there isn't, and if the network had >30 users before the previous firewall failed, then it can't possibly have been using a .224 subnet mask. Unless your organisation really
does have separate subnets in different parts of 192.168.200.xxx, set the subnet mask on the internal network to 255.255.255.0.
Peter