1: Should have + past participle can mean something that would have been a good idea, but that you didn't do it. It's like giving advice about the past when you say it to someone else, or regretting what you did or didn't do when you're talking about yourself.

Should have had or should have?

Had is the past tense of have and has, however, we don't use 'should has' even for 'she'. For example, she would have... (NOT she would has). Thus, always use 'should have'.

Should have done this meaning?

When you say "Should have done it", it means pretty much what you said "you were supposed to do it", and it generally implies that "you did not do it". But it is possible that you were "supposed to do it", (and) you did do it.