My first question. Is it better to preheat the smoker before loading the meat/fish? The manual recommends preheating, but I will trust your experience.
ND here to! And Welcome..
Yes , preheat it ...even if your short on time , give it a head start.
I have the MES40 with window and mine leaks thru the bottom window . Im sure its just moisture running down the sides and leaking out...you will find this is fairly common. If the new door helps, Great! If not, no harm.