First question, with my ETL software, I could map all GM contact fields and migrate them to MCRM contact entity. The only field I can't is the owner (the owner is then always the creator of the contact).
I found that they are privileges on this entity fields prvAssignContact.
Is their a trick to remove this security, or a thing I could do through the SDK Toolkit I just started to use yesterday?
On SO, I found this topic, Can I update the owner id of a Contact using LINQ? but simply don't know if it will be useful for me and if yes, where to put that code.
P:S: I definitely have to do it alone... so I would enjoy user-friendly advices!
In addition to Guido's answer, if you use impersonation on your IOrganizationService, it will automatically set the owner to the impersonated user.