Hi Diana,
Can the search fields in the header be edited so they aren't so HUGE? I'm assuming I'll also be able to use whatever size background image I want in the head if using a child theme?
Yes, but only possible through code customization. The theme is
not encrypted, so it can be modified according to your skills and requirements. If you are not comfortable with codes, you may contact one of Appthemes certified community partners
http://www.appthemes.com/partners/ or ask for help in our related forums.