For my first question, is it cool to give positive trust for transactions that I am not personally involved in? I don't want to come off as being a strictly negative Nancy. Quite frankly, I haven't engaged in any P2P on this forum since I am not a very trusting person.
How does that transaction make you trust the person? Perhaps if you had an example it would be easier to advise.
Generally speaking though - there is no need for affirmative action here. There is no positive (or negative) quota so whatever you feel needs to be conveyed to the community as (un)trustworthy - that's what you do. If that makes you a negative Nancy then it's more a reflection of the shitty state of this forum than your personal character.