In most conversions, camera EXIF fields such as the camera model and GPS position are not carried into the PNG. There is no setting on this page to keep or remove metadata, so check the result with a metadata viewer if it matters.
Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
Yes. Uploaded TIFF files are processed on our own conversion servers, no person reviews them, and they are never shared. The upload and the converted PNG are both deleted automatically about 24 hours after the conversion, which leaves time to download the result. See /privacy/ for the full policy.