Well, changing the background would be completely changing the theme, something I’m not comfortable with telling someone how to do to my theme. If you have a background in mind you can send me the link and I’d be more than happy to make a theme for it.
No, there’s not. I’m glad you asked, though, because I just completely forgot to add one. I’ll get to work on that right away. Thanks <3
Update: A new theme with an ask button has been submitted!