Mini-splits are really good for patio sized off-sets but they will be a little too much for a WSM..even the 22.5. Your best bet is fist sized chunks. I have split my mini-splits in half because I have a big stock of apricot but no apricot chunks and the mini-split cut in half works well but I only use the one split half otherwise it is just too much smoke........
Peach wood is a great smoking wood, I know Myron made it popular on the pitmaster series but I have used it for years...for a great flavor mix it with some white oak..........