We don't have our current time zone because of that. We have it because a fascist dictator wanted to be on the same time zone as Hitler.
And the logical timezone is of course GMT, the one closer to Spanish solar time. It's been proven that it's not healthy to be in a timezone that doesn't correspond to your solar time, unless you adapt all the schedules to follow the sun.
Yes. It loads faster, it has integrated quality levels that increase while loading (so a web hoster doesn't need to have 5 different copies of the same image at different qualities), it has better compression and it also supports more features. It can also be lossless. Most importantly, jpeg can be converted to jpeg xl losslessly, and it will have the benefits of jpeg xl.