Is it trolling if you are arguing the opposite of what you believe currently in a sincere non-inflammatory manner?

It is because you don't believe it and you're misleading people about what you really think.

Yes, but isn't the point of it all to get to the truth of the matter that exists independently of the debate.

The truth of the matter exists and it's what you really believe. Playing around with contrary viewpoints is just childish.

Why be so arrogant to think you're right and just have to convince the other person? Are you really convinced you know everything there is to know about the issue and can't learn any more from another person who doesn't agree with you?

etc...

No, it's called playing devil's advocate.

The best version of this is called "steel man-ing", as in creating the opposite of a straw man.

No, AKA "the socratic method."