Recommendations for setting up an Xserve for my office?

Question

I'm setting up a new office (we do operations research consulting) and we're doing an all Mac computing/networking setup with hopefully no IT support since overhead expenses are an issue for us during our startup phase. I've been using Mac's since "the beginning", but I've never setup a server before. We think we may need a server for the following reasons:
1. File sharing (we need to maintain project/administrative files as well as an online technical library)
2. Firewall
3. User account, etc. management
4. Hosting a corporate website (this is informational vs. transactional)
My questions:
1. Do we need a server? I'm pretty sure the answer is "yes" or at least that a server would be helpful.
2. Is it reasonable for a server neophyte to setup and maintain a network server for a small group of users (initially less than 5)? I'm hoping to spend no more than 4-5 hours per week doing this administration.
3. What specific Xserve configuration is needed for the uses listed above? Is redundant hardware (e.g. power supply) really needed?
Apologize for the broad scope of this question; any help you can provide will be most welcome.
iMac Intel Core Duo   Mac OS X (10.4.8)  

Answer 1

Everything DPC says is good advice.
I'm worried about the weeks of setup time required, however. What if I just initially use Xserve for network file sharing?
Weeks is an over statement. An Xserve will arrive with the latest system on it ready to run out of the box. When you boot it will be in "configure me" mode which is easiest to do from a remote computer. (Although the new Intel's do have video built-in.) If you have your ducks in a row - a permanent IP address for the server ready and knowledge about your local DNS system etc - you can get it set up quickly. For file serving you would then have to add client accounts, groups, create shares and add data to them. Five minutes is a bit optimistic but a couple hours with certainly reasonable. If you aren't used to the server environment tools I would add at least a couple hours for screwing around and documentation searching but if you read the Apple set-up guide before hand you should be in pretty good shape.
The server does come with a firewall - a pretty good one too. But there are a couple things to think about in terms of security that lead one to thinking a separate appliance is a good idea. When your firewall is run by your server on your server box then a security hole in the OS itself or a vulnerable service may allow someone to get at your box in a way that essentially circumvents the firewall. If you run a firewall that runs on a different system - BSD on an old PC or even a commercial firewall box - then someone would need to defeat the firewall device and then your actual server box. This raises the bar significantly and would probably preclude script kiddies and their ilk.
Another thing I would suggest is running the website on a sacrificial LAN on the other side of the firewall disconnected from your local network. Since webservers are a huge vulnerability in the network sense not running in on box that also houses your essential business data is just a good idea. I know that multiple servers - or server OSes - isn't practical for many people but it is still a good idea.
The bottom line is that an Xserve could/would do all these things for you. Don't forget UPS, rack mounting, cooling and data back-up as you plan your system. Also know that the Xserve is much louder than your average computer and you should plan for that as well.
Hope this helps,
=Tod