Contacting multiple professors for supervision I am an Honours student in the process of contacting professors and senior lecturers to request supervision/joint supervision.

So far, I had been in contact with a pair who were more than happy to supervise me, but after a meeting or two with them, I felt that
1) we probably would not click
2) their area of research, whilst on the outset seemed similar to my interests, is quite different.

So with that said, I have also been in contact with another pair.
These two seem extremely nice and supportive. I feel their research interests/expertise is more closely aligned with mine and that I would probably be better suited to working with them.

This is in Australia, so the semester will begin in about 3 weeks, and final supervisors are chosen in late march/early april - so I still have lots of time.

I wanted to know - should I flat out tell the first two academics that I am speaking to other academics, and may not end up going with them, even though the second set of academics are not confirmed supervisors?

Did I do anything ethically wrong? I feel bad for having had the first two (potential) supervisors have a phone/skype meeting with me + send me all their papers/manuscripts, if it was all in vain.

Finally, to add, would it be wrong to ask the first set of academics if I could be a TA for any of their classes, knowing that there's an 80% chance I won't be going with them as my supervisors?

Any advice is appreciated.
You should definitely shop around before selecting a research supervisor.  This is expected.  You do not need to declare it.  Just do not make commitments to more than one research team.  It is part of the faculty's job to compete to recruit honors students.  But prospective students have no responsibility to work for faculty until they agree to do it.