Turn each page of a PDF into a JPG or PNG image. Pick the pages you want and the resolution. Several pages download together as a zip file.
JPG gives smaller files and suits most uses. PNG is sharpest for text and diagrams.
150 dpi is good for screens and sharing. Use 300 dpi for printing.
No. Everything happens in your own browser, on your own device. Your files are never sent to a server, so nobody else can see or keep them.