SideBar re-size and re-position

If you look at the CSS for the sidebar, you’ll find this:

#secondary {
float: right;
overflow: hidden;
width: 28.125%;
padding: 1.875em 0;
font-size: 14px;
font-size: 1.4rem;
}

You can adjust the width to a smaller percentage.
I would recommend you make a child theme first. Have a look in the style.css at the top in the comment area, there are instructions provided if you’re not familiar with child theming.

As for your second question, I’m not exactly sure what you mean. If you can provide a link to your site, I can have a closer look.