As to the first problem it sounds like pilot error. Maybe you need to 2 step it until you figure out the misstep.
1. Open the image in paint, select all and press control+C
2. Switch to the email and press Control+V.
I have a new HP PC with Windows 10 and a Canon MP980 printer/scanner.
When I scan a document, the scan always appears in Photos. I then attach the scanned document to an email but when I open the attachment, in addition to the scanned image, all my photos are in the attachment. I cannot find a way of preventing the sacn from going to the photos file or extracting the scanned image from the photos file.