1. I've used both and frankly, its hard to tell the difference. Both leave a virtually identical gloss. Vinylex has UV protectants in it and I'm not sure what E1 has included. It may not matter as the Satin Finish
Tire Shine has been discontinued.
2. I don't think either will turn tires brown. I've used E1 for over 10 years with no side effects. Just amke sure you clean the tires during the wash.
3. Since both are liquids they can sling if you don't buff off the excess product after application. But if you do get some on the paint, no worries; they're both water-based.