Security advise on setting up a gambling Bitcoin site
Using Bitcoin means using maximum security

You can cut corners but you need to understand that by doing so you are introducing risk into your business model. These risks include, but are not limited to:


private key theft by malicious administrators
cracks through known vulnerabilities in virtual machine implementations
cracks through weak operating systems (use a secure Linux distro)
theft or confiscation of hardware (data centers may take your stuff)
domain name seizure (ICANN can and will)


To reduce the risk involved you need to isolate your Bitcoin code from your public-facing web code as much as possible. This usually means having your own dedicated hardware under your physical control. Often this means a machine in your basement with a dedicated VPN and static IP address.

Make sure that only the "float" part of your balance is accessible to the server in a hot wallet. The rest should be in an offline cold wallet requiring manual access to free up the funds. 

Remember: Bitcoin is money. Take the same precautions that you think a casino would take then go the extra mile.