How to migrate Attachments (Contacts) + Marketing attributes (Contact + Account)

Dear C4C Experts,

we are planing to shut down our CRM on premise system and replace it with C4C. The C4C system will be connected to ERP.

Now we would like to migrate selected data from CRM on premise to C4C.

1. Do you know how we can Mass import Marketing attributes into C4C (for Customers and Contacts). The standard migration template for customers is not offering a TAB for marketing attributes. Is it possible to do it via the new data workbench?
2. The new data work bench offers options to mass upload attachements and assign them to several objects. Unfortunately, we couldn't find an option to upload attachements for CONTACTS. Has anyone expierence in that ?

Exporting the data from CRM on premise is not an issue, it is all about finding a place where we can upload the data.

Cheers,

Wladimir