If I took the bus, I would now be at home. - This means that you don't usually take the bus - It's not your habit. The time reference is present - imagining something about how things are at present. This is called the second conditional.
If I were you, I would not have said such nonsense. - This is a mixed conditional because there is a reference to the present and a reference to the past.
If I were you - I'm not you, never have been you, and never will be you.
I would not have said such nonsense. - You said it. I didn't because I'm not you, but if I were you, and I'm not, I would not have said it.
Student or Learner