PHP/Wordpress expert required to help automate areas of website

Hello,

Would anyone be interested in working with me on a project using wordpress. I have the website setup but there are a couple of things that I need some help with.

I operate the website based on custom post types with custom meta boxes to hold the information about each book.

Members of the website only see the front end, so I am using the Gravity Forms plugin to enable them to upload their e-books to the website. This has options for prices, offers open, coming soon etc.

Short Term:
Once a member has uploaded a book then can "edit" it. So they can upload a new cover for example. I need a way to have the file upload process delete the old cover and replace it with the new uploaded cover. The covers are held as featured images for the custom post type.

The same goes for if they edit the book itself (which leads into the long term issue I have) - ideally if they upload a new book file, it will automatically convert it and replace the existing files on the server for the book.

I'm also starting to get more books on the website, so having better ways to display them (and filter them by price, "coming soon", offers = "yes" etc would be very useful.

Long Term:
Once a member has uploaded their e-book, I am then having to convert the books manually to the following (which I use a program called "Calibre" for). I can cope with this at the moment, but if the website gets popular it's going to be unmanageable:

1.) A sample of the book (which I take to be about 10% of the book) saved as a .pdf file
2.) A .mobi version of the book (to be read on kindle books)
3.) A . epub version of the book (to be read on iPad, iPhone and other e-readers)

If I could automate the book conversion process it would save me a fair bit of time which I could then use to improve other areas of the website.