Hey Jay,
Please see some answers to your questions below:
1. The below Custom CSS should move it down a bit for you:
#responsive-menu-pro-header #responsive-menu-pro-header-bar-logo img {
margin-top: 15px;
}
2. %
options is the correct way. That mixed with a minimum width, so it doesn’t get too small on mobiles and a maximum width, so it doesn’t get too big on desktops should be all you need.
3. You need to enable the Header Bar option and then for the background, select a colour and drag the opacity bar on the right of the selector down a bit.
I hope that helps and if you have any more questions please let me know!
Peter