You use Java in a lot more things than you think. Java Desktop Apps are terrible and the updater is annoying as hell, but it's also likely the language powering most every device you use and many web applications you use day to day.
The E-10 has been murder on my late 70's vehicle -- I've had to replace all rubber gas lines and have to tinker with the carb much more often. I highly prefer 100% petrol. Stabil seems to help when I have to use E-10. I haven't noticed any issues (even change in mileage) in my 2005 car however.