WebP is usually the right answer for images on a website. It compresses far better than PNG, supports transparency unlike JPG, and every current browser reads it. For graphics with transparency in particular it is strictly better than the alternatives: you get PNG-style alpha at roughly JPG-style file sizes.
Yes. This is WebP’s main advantage over JPG. Transparent backgrounds, soft shadows and anti-aliased edges all survive intact, which is why WebP suits logos and UI graphics so well.
It varies with content. Photographic PNGs often drop by 70 percent or more. Flat graphics and screenshots see smaller gains, because PNG already compresses those efficiently. The tool shows both sizes after converting so you can judge whether it was worth it.
Yes. Chrome, Edge, Firefox and Safari have all supported WebP for years. The remaining gaps are in older desktop applications rather than browsers, so if the image is for the web you can use it with confidence.
Yes, if the image is a source asset you may edit again. WebP here is lossy, so treat it as an output for publishing and keep the PNG as your master copy.