MISC-----mishna brura

I thought we paskin like the Mishna Brurah (at least as a general rule). Isn't that why they print the Kitzer Shulchan Aruch with oiskei M"B? Wouldn't it be more advisable to learn the M"B?

Depends who's the "we". Jews of Polish or Hungarian background don't, Chassidim don't, especially Lubavitch who as a rule follow the Rav Shulchan Aruch, Sefardim don't, Bnei Brakers and Chazon Ishniks dont. Much of the Litvishe world, which is where the Chofetz Chaim was and had his strongest influence, use the Mishna Brura as a general way to pasken, often. But not always. Rav Moshe Feinstein often disagrees with the Mishna Brurah and his followers follow his psakim. There is no official rule that "we" pasken like the Mishna Brura like there is that we pasken, say, like the Rama if youre Ashkenaz. Rather, where halchah is concerned, the Chofetz Chaim became like the Rebbi of many communitites, and they accept it as such. Also, the Mishna Brura only includes one part of Shulchan Aruch, Orech Chaim. The other three sections are not covered by it at all. And although the MB is extremely comprehensive in that section of Shulchan Aruch, the Kitzur deals with money laws, kashrus laws, tznius laws, and things like that which is covered in MB.