Hi Dan.
First of all, congratulations on getting the new toy. Hope you have lots of fun with it
As for the topic at hand; that's indeed how it works. You can essentially configure it in two ways:
1) Assign the AF-ON function to whichever button you like (AF-ON, shutter half press,...). Assign your FN buttons to other AF area modes WITHOUT AF-ON. In order to acquire focus, you'll always have to have your AF-ON button pressed in conjunction with the AF area mode button of choice.
2) Assign buttons to AF area mode WITH AF-ON. In this case, there'll be no need to keep the initial AF-ON button pressed as each individual button will initiate the focus process as well. When using this way of doing things, it's also a good idea to make sure you have custom option a7: focus mode persistence enabled. This allows you to switch between modes without AF starting all over again (if you have acquired focus with one AF area mode, pressing a button for another one will seemlessly take over).
Both are perfectly viable options. Just a matter of preference. Hope this helps.