It all depends on the editing possibilities within your theme. Many themes have settings for lef, right or no sidebar on frontpage, category pages, pages and posts.

It can be relatively simple if the theme you are using has a template that removes it for you.

Go on to the edit part for the page you want to remove the side bar on, and have a look under template. There may be one called something like "no sidebar" or "full width".

Other options are using a plugin, or creating a child theme and removing yourself(a bit too advanced I feel for now).

In summary-Look for either a template, or a plugin.

check out this:
http://www.wpbeginner.com/wp-themes/how-to-hide-the-sidebar-on-your-wordpress-home-page/

Hope that helps

Just tell her what you do and ask her if there's a way to get something going.

I think you should set up the relationship in whatever way you both feel comfortable. Clickbank or something similar would be easiest in terms of linking purchases and payment. You will want to be as hands off as possible so purchases don't become an adminstrative nightmare.

Many of the ebooks I have received are in plain .pdf format.
So the easiest to do is to use Word or a similar text editor and simply save as .pdf.
There are many design features in Word that can make the ebook visually appealing.
If you plan to write for Kindle or other readers, there are tools for that.