IP Addressing

This question deserves a long description but, I'll try to be brief.

The use of public IP addresses means that every host on your network has the potential to be known outside of your LAN. With that in mind, you must provide the extra step of setting up your firewall to block all unwanted traffic from these hosts. The most acceptable way to accomplish complete protection is to block all inbound traffic (set this as the default) and then selectively allow certain inbound packets such as SMTP,FTP, or HTTP to certain hosts.

Keep in mind that, although you are using public IP addresses, you can still use NAT. So, if your concern is that your LAN is at risk through the use of public IP addresses, go ahead and use NAT to mask all of yourhosts from public access.

Lastly, if your concern is the number of IP addresses available to your LAN, you must consider 1) what your ISP is willing to allocate to you and 2) what you will have to pay for additional addresses. Keep in mind that when a network grows, you will often find yourself in the situation of having to manage 2 different segments of valid IP addresses, maintaining a router between.

If this doesn't cover your concerns, please repost with more specific requirements.