Yes, hopefully this is that easy, but applications are dependant on what their developers do, so it may not always work like that.

Is this Family Tree Maker the same version that you had on the XP system? If so I would certainly try what you suggest. Copy the file from your backup to the Desktop on the new system. Then open FTM. What happens next is dependant on the FTM application itself. Does it have a File > Open menu option? If so, simply goto File > Open, navigate to your Desktop, find the file and click Open. If it doesn't work that way, does it have an Import/Export feature? Import is often a name used to open other files, eg my Firefox browser has an Import feature for importing saved bookmark files.

With the other files it all depends what they are and what software uses them.

One thing you need to consider. This 'backup' on the external drive. If this is now the only place where these files are, it is no longer a backup. It is your only copy of these files.

Not meaning to be alarmist, but I needed to mention it.

I hope that helps.

Mark