|I hate to break it to you but if you don't already know about VLAN's and VLAN tagging and how to program VLAN capable switches you need to get some training on the aforementioned.|
Trying to do a project like you described, on your own, without a decent level of knowledge in the subject area is begging for trouble. Not to mention the fact that the time it takes to configure and deploy said project will be huge compared to if you already had all the necessary knowledge.
My best advice to you is to hire a reputable consultant to do this for you. If you hire the right person, they might even be willing to teach you some of what you need to know. The rest you can learn on your own.
At present, you don't seem to have enough knowledge to maintain such a setup, much less configure and deploy one.
There are other considerations you need to take into account. Mainly, security for your data. VLAN tagging and bridging do not supply security and anybody with a packet sniffer could grab your traffic and data. So you would need to also add encryption to your data and likely will need VPN's of some sort between sites.