I came from the Thunderbolt as well and it must have been the SD card as the Thunderbolt SIM card is too big for the Note 2. It's an older standard size SIM, whereas the Note 2 uses a microSIM card (came with the phone when I ordered it).
As to your contacts, I'm guessing they were stored on the phone itself and not backed up to Google or anywhere else? If you still have the Thunderbolt, you can export them to the SD card. In the People app, hit menu, Import/Export, and choose Export to SD card. It creates a file called pcsc_pcsc_00001.vcf (it will increment a number if a file already exists) on the root of the SD card. To restore them on the Note 2 (after you?ve swapped SD cards), bring up the Contacts app, hit menu, Import/Export, and choose Import from SD card and select the appropriate vcf file if prompted.