In order to add ACT! note dates (or/and any other columns) please follow the steps below:
1. Follow the steps as outlined in the Salesforce online help file for exporting notes from ACT!.
See Exporting from ACT!
2. At the step where you add the "Regarding" field, also add the other note field data you wish to export.
3. Continue with the steps as outlined in the Salesforce online help file.
4. When importing the .CSV file into Salesforce, only map the company and contact details at the initial stages.
5. In the final step of the import wizard you will be prompted to "Map Extra fields", in this stage map your ACT! Note fields to "Include in Contact Note". This will import into the note section of Salesforce.
NOTE: Each column that you choose to import as a note will become a separate note. The title of the note will be the name of the column from the import file. The body of the note will include the cell contents from your import file.