May I? :)
When something is "peachy", it means it is all fine and good. "How are things with you?" "Just peachy!" If a person is "peachy", it means they are attractive. In English, "peach" has very positive connotations - like a fresh peach.
(I'll just had that my own name has nothing to do with the above meanings... or even with peaches.)
"Keep both hands on the wheel" is a driving analogy. It generally means, "stay focused and in control of the situation". As if you were driving.
"Above my paygrade" is an idiom used to mean that something is beyond your ability or knowledge. The suggestion is that someone who would be paid more than you would therefore have the specialised ability or knowledge... so they should be asked, not you. It could also mean you don't have the authority or, as Steph points out, you don't want to because you're not "paid" enough.