You should be able to use at least SOME of your old voices.
But firstly, the vioce "set" should consist of these files:
dataxx.chk
dataxx.vif
dataxx.bmp (optional - the icon)
dataxx.tlv (optional - ONLY used by TT Home for it's own purposes)
So you do need to find those .vif files. They are the link between the voice name and the "xx" number in the file names.
If you open a .vif file in Notepad, you will find the voice "name" in there.
To add these voices to the new TomToms, you use the "Add community content" feature in MyTomTom.
Launch MyTomTom, and click on the icon in the system tray (next to the clock).
Select "Add community content" and a browser window will open.
Scroll down to "Add voice" and click on it.Then click on "Browse"
You'll get a standard file selector, use it to find the .chk .vif and .bmp files (the .tlv is unnecessary)
Click on "Open" and then "install" back in the main window.
That should work for the FREE voices you have.
I suspect the paid-for voices will be locked to the device they were purchased for, so they won't work. It's worth a try... but I doubt it.
The voices will be installed directly onto the internal memory, unless there isn't enough room, in which case you'll be asked to insert an SD card (which will need formatting in the unit)
There's no folder to put them into, because the new units don't use the standard PC-type of formatting and file structure. That's why you need to format any SD cards to TomTom's own format on the device itself.
Finally, no I don't think TomTom will ever get round to launching a similar download site as they did with Home.