What is my best network option?

[myst3]

I'm currently setting up a network system for my business. I have 6 small offices in 2 buildings. 3 offices in one building and 3 other offices in another building. The buildings are separated by a small lane less than 20 meters wide. Each office has its own telephone connection. I employ 11 staff, each will have access to his or her own desktop. That's 12 desktops altogether, including one for me. Here's what I need to know:
1) If I set up a LAN for each building, how can I best connect the 2 LAN? Or should I just set up one LAN? If so, how to best connect the desktops from 2 different buildings?
2) Can a wireless network cover the range of the 2 buildings?
3) Can I just get a single server powerful enough to act as a file server, print server, email server and application server? Or should I get an individual server for each function?

Thanks.

[johnwill]

First off, if you're going to have a file server, wireless between the buildings will be a limitation, since it will really impact the file access speeds.

A single server will easily serve 12 workstations doing almost anything, that's not the issue. If you use an 802.11n link between the buildings, you'll have decent performance, but nothing like a wired connection. Is there any way to run a fiber between the buildings?

It will be much easier to manage with one server and one ISP connection, not to mention cheaper to install and maintain.