At JPG 90% it looks the same. Keep the HEIC as the original for editing.

Do date and location survive?

The date taken does, unless you choose "Remove" under Date taken. The location (GPS) and camera are always left out.

Open iPhone HEIC photos on Windows

A HEIC someone sent will not open. As a JPG it opens anywhere.

Drop the photos on "HEIC to JPG". One at a time is free; batches with the Pass.
Quality 90% is plenty. Save, and it is a JPG.
For the future, set the iPhone camera to "Most Compatible" to shoot JPG from the start.

Does quality suffer?: At JPG 90% it looks the same. Keep the HEIC as the original for editing.
Do date and location survive?: The date taken does, unless you choose "Remove" under Date taken. The location (GPS) and camera are always left out.

Pictures are never uploaded; the work is done in this browser.