Some answers ...

1 - Is there a way to modify the existing artifact via an import? For example if I take the example of a data artifact with ID=1 and data-type=String. I tried to update this artifact via a CSV where ID=1 and data-type=Numeric.
=> each time I try it, it creates a new artifact. This should not be the case right?
[dmoul] working as designed for V4.0.  See prioritized enhancement for 2013 and feel free to add your "vote" in the work item: 44296: [RM] CSV import / Export (Round Trip Capability)

2 - When I try to reference a link in a CSV, I have always issue during the import because RRC is not able to find the link. I don't get what make an artifact unique an how you can reference it in a CSV.
[dmoul] currently you cannot import links while importing from CSV.

3 - Is only text artifact format supported to do CSV import?
[dmoul] yes this is a limitation of the CSV format

4 - When I add an artifact to a dataset , I would like to automatically create a link between the dataset and the artifact. I know Ana is able to do it but I was not able to reproduce. Concept of hyperlink.
[dmoul] I'm not sure what you mean by a dataset.  With collections (and modules in  new in 4.0.1) there is a notion of "containment" (an artifact is contained in a collection or module.  Explicit links do not need to be created between the container and the artifact.


Note that the ReqIF format allows import of non-textual artifacts and links, however we do not currently provide an easy way to get data into ReqIF format.