is it possible to migrate directly from v10 to v12, or do we have to install v11 first ?
Yes its possible to migrate directly
do we have to open and store all qvd in the new version ?
I think its not necessary but its recomended that you test the documents using the Qlikiew Desktop of new release
Are there any specific points to be taken into consideration ?
be ayere of the loosing the licence information of the users and test your documents in Qlikview Desktop first.Backup of Qliktech folder is high recommended
is there a documentation explaining the migration process ?
Yes in help session of qlikview