LMDE 6 has only been out for less than a year. It's based on Debian 12. Debian 13 will likely be out around this time next year, and the future LMDE 7 will be based on that.
Yes it does, regularly. Don’t know what that person is talking about acting like it somehow wouldn’t.
They update Cinnamon regularly, and the main release is updated when Debian has a new stable release. This makes sense, since it’s based on Debian instead of Ubuntu. LMDE 6 is less than a year old.