its easier to jail break using greenp0ison's absinth one click jail break.when using redsn0w you can flash the ipad baseband to unlock but i would not recommend as its not reversible.
you can down grade to 4.1 if your shsh is backed up in cydia i.e your phone was jail broken while 4.1 was installed but then upgaded to 5.11 ect if not then its not possible to down grade.