Restrict image selection but allow copying text in pdf

I’m working on writing a technical ebook on Adobe Indesign. There are many engineering drawings and smart-arts (in .png format) which I want to include in it. When I export the book as pdf, the images that are included in it show selection around them when clicked. I want to make the image indiscoverable by the user i.e. the selection should not appear as if the image is part of the text and not like a layer stacked upon it.

Adobe Acrobat Pro 11: I have some sort of grid design I cannot alter

I used a PDF export feature in LogiReports to create a PDF. This shouldn’t much matter, because I have Adobe Acrobat Pro and should be able to edit what it exported. It’s created a report with a gridlike design of boxes (it’s not perfect grid; see picture). The thing is, I cannot figure out how to alter or get rid of this grid in Adobe Acrobat Pro. When I use any PDF-to-HTML converter, this grid gets turned into a full-page PNG.

When creating PDF from an image, what determines the screen dimensions when viewed at 100%?

I would like to use pdf for ease of use and annotations when creating previews of my screen designs. However, no matter how I create my pdf, I can’t seem to figure out what determines the 100% view of my pdf file. Naturally, I would like my pdf 100% view to be the same size on screen as my photoshop layouts – how do you achieve that?