I just cut and paste the IPA from Wikipedia! For actual pronunciation guidance I asked a native Russian speaker!
[Edit: I think it's possible in the IPA that the t is there to make it a harder ch sound like in check, rather than soft as in chagrin or chalet, kindof like the d in Django makes it the hard j common in English, as opposed to the soft j natural in French]
Don't know. When I think about it, all Russian ч (ch) pronunciations are consistent unlike some other sounds that vary depending who is talking. Not sure why they'd want to add anything to it. It's an easy sound from get go.
My personal pet hate is how Andrei Tchiml's[1] surname creates unnecessary difficulties for English (and other) speakers. It's a simple ch sound at the beginning and yet everyone stumbles on it trying to speak out a mouthful of consonants while they're not there to start with.
French, I think, are particularly having trouble with it.
[Edit: I think it's possible in the IPA that the t is there to make it a harder ch sound like in check, rather than soft as in chagrin or chalet, kindof like the d in Django makes it the hard j common in English, as opposed to the soft j natural in French]