Hi, I am Tumblr themes author, and I can deliver/complete your list of the customization as soon as possible since I have a vast knowledge in Tumblr themes operators (and Tumblr API if required), HTML5; CSS3; and jQuery. That is what Tumblr requires for building a nice sleek theme, or customizing in your case.
PS: the current bid budget, that's what I think of for the a starting price. The budget may trend down or up per your theme customization requirements list.
Regards,
Adam Azad