Hi,
No, the TyTN I and TyTN II use different batteries and cradles, so you cannot use your old cradle and any spare batteries you may own from the old broken machine to the new one.
They both use a mini-USB port, so Sync Cables, Mains Adapters and Car Chargers (chargers, not holders) are the same and can be swapped freely.
Windows Mobile 5 devices use Microsoft ActiveSync 4.2 or earlier, but Windows Mobile 6 devices require version 4.5. Only recently have TyTN I machines been factory supplied with Windows Mobile 6, so the chances are that you will have ActiveSync 4.2 installed on your computer.
If you buy a WM6 device, then ActiveSync 4.5 will be supplied with it. If for any reason you do not have it, you can download it free from the Microsoft website.
Regards
Ivan