massugu na kishou

Forgive me for posting again so soon after my previous questions.

1. What does it mean to have a 真っすぐな気性? Does it mean to have a straightforward, direct manner; does it mean to have a level head and calm temper? The examples I find online are rather vague.

2. だのに、本人曰く「自信のない」とは、なんともはや。
I don't understand the function of なんともはや in the sentence. The one example I can find suggests that it means that the "jishin no nai" conclusion is a rush to judgment, but I've not encountered this particular construction before.

As always, thanks for any help.

1. When it is used to describe a temperament/personal trait, I take it as someone who dislikes anything bent or wrong, so someone who would not lie, who would follow his/her passion without thinking about whether that would be to his/her own benefit, who would follow his/her principles rather than make exceptions, etc. "Honest" does not cover all of these meanings, but might be the closest :)

2. "... but the person him/herself says "I have no confidence," which is amazing."

What you must have read was "nantomo haya(i) " = how extremely quick/fast.
But I take this to be an exclamation of disbelief about what the person him/herself says.

Thank you, particularly with the "nanto mo haya"; I didn't recognize the significance of the "haya" element without the "i" attached. I appreciate it.