Hi Tree - I will have to cancel and remove your domains in order for you to delete your blogs. You have:
* domain sexinthemountains.com mapped to blog sexandthewilderness.wordpress.com
* domains sexandthewilderness.com and summitsustenance.com mapped to blog sexinthemountains.wordpress.com
Can you please confirm which of these domains you'd like to cancel? Please note that if you cancel it, there's no guarantee it will become available to register again. If you want to use it with another site (not at WordPress.com), you should transfer it rather than cancel it.
Also, I'm not sure if I can have a different header picture on each page of my blog, and if I can upload graphics
There are some themes that use featured images on posts to display as unique headers on those post pages, and there are also some themes that will let you upload a number of header images and choose that they be displayed randomly cycled through.
For the former, check out these themes:
For the random header images, I know Twenty Eleven is one such theme:
I'm not sure what you mean specifically by uploading graphics? You can upload certainly upload images - .png, .jpg, .gif.