iPhone photos are saved as HEIC, which many websites and Windows apps can't open. Convert them to standard JPG in seconds, in bulk.
At quality 90 the difference is not visible. You can raise it to 100 or set a target size if you need smaller files.
Yes — in 'Watermark, names & copyright' choose Photo info → Keep credit. The GPS location is always removed for your privacy.
No. Everything happens inside your browser, on your own device. Your photos are never uploaded, stored or seen by anyone.