menu is shaking when I scroll-over

For starters, you should have been working with a child theme rather than editing the main theme directly, as discussed in the Codex. (Although actually, @import is not the best method, for the reasons outlined here.) That said, given that you’ve already made quite a few direct edits to the main theme, creating a child theme now might be akin to closing the stable door after the horse has bolted.

Anyway, I think the relevant CSS rule is this one:

.genesis-nav-menu .menu-item:hover {
	position: fixed;
}

Delete or comment it out.