What can be transferred to SD 7.5

Dear All,

After reading several posts about SD7.5 and transferring data, I lost track about what can be transferred from 7.1 to 7.5. I thought that closed tickets were no problem and open tickets were no option. Is this correct? What happens with numbering of tickets (e.g. IM-002583 is a closed ticket, we transfer this to the new system, will the new system start with IM-000001 and skip IM-002583)

What about Knowledge Base articles? What about User Management (permissions, groups, disabled users,...)

Thanks for the info

Kind regards

Koen