Who can help me?

in cleft sentences
it is i that am happy
it is me that is happy
which sentence above is correct?
in repoted speech
the man said that he visited London in 2001
the man said that he had visited London in 2001
which one is correct?
(grammarist said that we don’t change the tense of sentences with year in them “the man said " i visisted London in 2001”)
in tag questions
someone washes my car doesn’t he?
someone washes my car don’t they?
she has two brothers, doesn’t she?
she has two brothers, hasn’t she?
which sentences above are correct?
please explain to me tutor.

I figured this out. We will wait until the people in Europe have their breakfast and have them answer this.

If they do, then we’ll know that they know the language better than we do. I don’t mind being dumb if it gets me out of answering questions.