To Jiuzhaigou, Mt Emei, Leshan early Nov. Will landscape be as colorful as in Oct? Is weather cold?

Yes, it is enough to cover the places you metioned. But if you go to JZG, it is suggested to go go Huanglong by the way, and then your jouney may be in a rush. But not so bad.
It is a good idea to join a local company or you can contact TravelChinaGuide, which can help you arrange your routes according to your requirements.
To be honest, it is not so beautiful as in October, but not so bad.