The "t" in "comment" is only pronounced in that one expression that you mentioned. As far as the final s, and many other final letters, you should do a web search on "liaison."

We can find this T sound in other expressions like tout a coup which means suddenly and here you have to say : tou't'a cou ( the p is silent ) : touta cou ! And normally here also the t sound isn't proununced when the word " tout "comes alone but " la liaison " impose that you pronunce it

Here we're talking about " la liaison " and it's about sounding more advanced and to avoid speaking like a robot I mean like in english you can say to an native friend : what are you doing ! He will understand that but you'll sound like a biginner, a good quick natural pronunciation would be like : watchyu doin' so it's the same right here Comment allez vous : you can notice the presence of the T at the end of " comment " which is normally not pronunced and sound like common but here to add a ' liaison ' between the words and make it all together like a building you have to pronunce it like Commen't'allez vous Vou's'etes intelligents = vou' z'etes..( s usually sound like a Z sound in the middle of words while the s is with " ss " if you want I'll talk more about that )