Yes and Yes
I'll start with your logo size first....
1) Here are the elements in the template file to change. [marked in bold]
#s5_logo {
cursor: pointer;
float: left;
height: 79px; margin-bottom: 6px;
margin-left: 0;
margin-top: 11px;
width: 87px;Now? There is possible "width limits" in which if you make your logo too wide, it could affect something
2) May I ask what browser you are using?
3) I have have just installed this myself to test it and used the SiteShaper, so I have not tried inserting a logo yet to see what breaks and I plan on changing colors also...but that will be later.
J