This would be correct. If you have VMS 2.1, it will have IDS Management Center bundled in the package, which you can use to manage your sensor(s). CSPM will still be a solution also, as will the Unix Director and IDM. What you use should depend on the number of sensors and what features you will need to support your IDS solution.
Yes, we already have many customers who have successfully installed and are using IDSMC.