miui is just android, if you dont like that 4 icon launcher then install Launcher pro. it has an app drawer and youll never notice the difference (except in settings menu and other areas that miui has customized)
its the same reaosn why you install Go Launcher or LauncherPro to replace that useless 3 icon dock that stock gingerbread has.
and yes i highly reccommend the mock kernel, changes everything makes things faster. i dont believe it comes in the rom as is.
also, "Extended Settings" for miui, from the miui forums, you have to mount /system in recovery, flash the 11-25 version of extended settings, and there will be an app that lets you change everything about the status bar, color, transparency, carrier logo with custom text, icon locations. its really a must have, but you gotta look for it at miui forums
although, CM7 reloaded has had so much development that it kind of outweighs how pretty miui is.
at this point id stick with cm7 and wait for cm9 or miui v4 to be stable. thats what im doing at least.
but i do LOOOOOVE miui. the lack of rotation animations kills me after having it in cm7 reloaded