Could you explain the decision process behind using fixed IP addresses? It's not my area of expertise, but surely using a URL would provide you just as much control with vastly more flexibility.
Fine, get the first version in front of users sooner rather than later. But if you are not in a position to recover from an intrusion, disk failure, fire in the server room, etc. you are not ready to have users. You really need to address all those concerns before the first line of code is written, as without it all your investment in development is at risk.