1. RAW file will be between two and six times larger than a JPEG file. RAW files are bigger because they contain a much greater amount of image data. A JPEG image is essentially all that data compressed down into a smaller file size that’s easier to share.

2. A RAW file is bigger.

3. Yes you can change the files. The way you can change it opening the photo in photoshop go to “file” chose “export as” and select from the list.

4. It would be better to shoot on Raw because  the format captures the highest level of detail. It can often be easier to edit exposure later with a RAW file. But shooting on JPEG often does have it benefits since their smaller file sizes allow you to shoot more images at once and transfer files faster.