Happy Holidays to you as well.
Any hardware setup you would likely use is sufficient. If new, they will be good. I even ran V4 beta on a 400 MHz Win 2K machine. I prefer XP to vista, less memory needed but both will work. Any dual core is fine.
I would recommend hard wired with 1K router/switch. Wireless is much less predictable, slower and less secure.
Faxes: many use Brother 7840, I have one office running on win fax. former is somewhat more reliable. You might also consider one of the internet incoming fax services. All will give you files as PDF. (Well, winfax won't, but easy to convert.)
We have 2 offices and they have separate databases. You could try running a VPN, it would be somewhat slower, maybe not at T1 speeds, but T1 would need to be on both sides. Syncronizing is not perfect on AC yet, (I haven't tried it on V4 beta yet.) It is one satellite or 2? More sites make syncronizing impractical.
Server vs desktop. Server will allow more connections, but with 3 providers and even 4 staff you could run peer to peer. You would need backup service, but there are many programs that would do it for you.
