Is there any way to export user account information and content profile together? I need to export all the information of a few user accounts and relevant content profile nodes together per user.
It doesn't matter what format it should be but I'll eventually import back to the same site.

It seems that View Bulk Operation does the job but in the Views I must include all the profile fields,CCK fields and all the rest of the information the account and the node has.
So it's just not realistic in my case.

Is there any way I can export all the data that belongs to one user ?
I would still go with Views, unless you want to do it in your own custom module as suggested in the other answer.

There is Profile CSV, but this is limited to user accounts and core profile fields. There was a feature request for Content profile, but that issue wasn't finished, and in fact a Views-based approach was also suggested in that thread.

You can build a view of user account fields and related CCK views using Views relations, and export to CSV using the Views data export plugin. (And you can later import CSV via User import).

I believe any solution other than Views requires coding.