Re: 12 imam concept of shias
Islam doesn't say anything about 12 imams or anyone for that matter after Mohammad's (saww) death. Don't forget, Islam was all done after Mohammad's (saww) death and that is where people started dividing in groups. The matter of 12 imams is a shia belief.
As for the 12th imam. Shias believe that he was Imam Mehdi who has appeared before (if im not wrong) and he will appeare again on the day of judgement when dajal will appeare. Although sunnis believe Imam Mehdi will only appeare on kayamat.
About making something halal haram, that could be a misunderstanding. Even Mohammad (saww) didn't do that then how could the imams? Allah is the only one to decide what is halal upon us and what is haram.
Zer01:
Would it be possible for you to name the 11 imams if you don't mind?