Debian :: Tips For First Time Server Project?

My distribution of choice on my desktop is Arch Linux (I like getting all the new stuff before anyone else) but I am going to be making a home server, and I can't imagine Arch Linux working well for that because I want something stable and reliable. I always admired Debian for not only APT but it's reliability. I thought about using Ubuntu server but I don't like the direction Ubuntu is going, and I like Debian better anyway, so I am firmly set on using Debian for this server.

This server will be more advanced than necessary for a home user. The reason is because it's a learning experience. I want to learn all about DHCP, DNS, and all those other things. I'm already very knowledgeable on SSH and Unison, which will be the primary focus (backing up). So I was hoping I would list the things I decided to do and get some opinions/best practices from you guys.First, I decided on a Dell Inspiron 570. It's dirt cheap (around $280) and it has a gigabit network card. (I'm pretty sure). I need to stay as cheap as possible because money is a HUGE factor for me. I have a budget of under $700 to do all this. (So I may need to get smaller hard drives). Whatever default hard drive it comes with I will add two more hard drives in a RAID1 for /home. Like this:

Disk 1: Root, swap and boot partitions (smaller hard drive)
Disk 2 & 3: Dedicated to /home, on a RAID1 (two 2TB hard drives)

The idea is that once the server is all the way done, I will image Disk 1 with Clonezilla, and if it fails, just restore it. I personally don't feel that having RAID1 for the root partition is necessary when Clonezilla takes 20 minutes to restore a drive, or less. The OS and all configurations in /etc would automatically be backed up in that image.Since I'm using the server primarily for backups (there won't even be a monitor on it when done) /home will be on a RAID1 since that's the most important thing. (I have backups on external hard drives too, one is off-site, so still no worries). Also, the server will handle DNS for the hostnames on my four other computers, and I'm thinking of replacing my router and having my server do that too. Nothing wrong with my router, but it would be fun for me to set this up.