Multitiered Colo Setup

I just acquired a Dell PowerConnect 5324 and am trying to put together all my accumulated gears as close to an enterprise setup as possible. I'm relatively knowledgeable on the logic/software configuration, but I'm pretty new to network design and setting up switches/vlans. Your input on how to configure them in a data center environment would be greatly appreciated.

1 Dell PowerConnect 5324 with 24 port of gigabit NIC
2 Adaptec Snap Appliance 14000 with 2 gigabit NIC
5 1u IBM x335 with dual xeon, 2 36GB SCSI 10K drive, 2GB RAM, dual gigabit NIC, chain cables and KVM kit. (To be purchased. All the mentioned 5 servers would cost me around $3,000 total. Seems the best I could get, since can't spend more than 3 grand. Any other suggestion on picking up the servers?)

2 x335 will host apache httpd and apache tomcat clustered (Dell 5324 needs to act as a load balancer.)
2 x335 will host mysql clustered.
1 x335 will be the used to host the ordering, billing, help desk, and act as a management server for all other devices.

2 Snap Appliance 14000 (thinking to go with RAID 5) would be connected via iSCSI. They will serve as email repository, document repository, system logs, and as database repository.

Here's diagram in my mind

Internet
|
Load Balancer
|
/
----------------------------------- VLAN 1
| | |
httpd httpd monitoring
/tomcat /tomcat /management
| | |
----------------------------------- VLAN 2
| | | |
mysql mysql fileserver fileserver

Questions:
1. Your thoughts on the design of VLANs for the layered diagram?

2. Your thoughts setting up this Dell 5324 as a load balancer?

3. How to setup the VLANs if the data center's router only gives me one default gateway? Do I need my own router with at least two gateway interfaces?

4. As for email server, since it needs to be facing DNS server, I would think the front-end http/tomcat servers are the only place can host the the email server. Any other options?

5. Any other options on selecting the 1u servers?