There is 2 different things. Moshiach and who is moshiach.
Moshiach is def. A central core belief and attitude in chabad.
Who is moshiach is a personal belief.
For ex. I personally believe the Rebbe is moshiach and i say yechi, however i don't discuss that with others unless i am asked. My sons don't wear yechi yarmulkahs. I don't tell guests/mekuravim.. to say it.
However at a simcha it will be sung (ie I'm not hiding it )
The extreme side would be flag waving, pushing yechi in others. ...
The other side of the extreme would be not allowing yechi to be said in a lubavitch shul or at a personal simcha (yes it's happened ) making sure to write zia...
Most people are in between. Either they say yechi or not but it's not a big issue
Everyone talks about moshiach.
In my kids school they learn inyanei geulah and moshiach. A few lines a day or a week about the times of moshiach