Sounds like you have a BENGAL!!! Just kidding it sounds like he is a handful!!!! It could go in a few different ways! He could mellow out with the addition of a new kitten, he could become more amped up with playing and getting into things for attention and start to bully or they could become best friends and he could use all of that Bengal wild energy into play
Who knows really what will happen. I know that is THE ONLY reason I dont have another is because BB is so good and content with her being the only cat! You really have to weigh the options. If it turned bad how would you deal that? For now though I dont think it would be wise to get Charlie. I know he is laid back and BEAUTIFUL but the thing is, I know you would want a more laid back Bengal, but is that what would benefit Stash? Would he like a more laid back docile buddy or would he rather have a buddy that is more like him and more on his level. I think the later would work out better for the both of you!