Intern in need of assistance

I have been asked by an Intern Employer to tackle a project I know very little about, I will give as much detail as I can and hopefully someone can provide me with some answers. They currently have an old trixbox 2.2 system running at a 2nd location away from my current work station. They have had repeated issues with the older system as it has been failing over and over again. They want to upgrade to a newer tower running version 2.8. they use a VPN to route calls from this facility to the facility here through 2 firewalls at each location. My question is whats the best way to ensure that the new box will work when I hook it up and power it on? I have been unable to find a proper way of backing up the 2.2 system and restoring tot he 2.8 system, so I merely went through their FREEPBX setting and entered all the extensions, ring groups, ETC into the newer 2.8 PBXsetting.

Is this the best method for this so that the phones will find the DHCP and work once powered on? it’s a 3 hour drive to the old systems location and I would like to be as prepared as possible to make it as easy a switch as possible, Everything I know of trixbox has been self taught to this point so any help would be extremely great.