1. Read this thread!!!
2. ADFA; about 3 years. Pilots course; about 18 months. Time to complete F-18 OCU; about 18 months (varies). Therefore you're looking at 6 years, all things going well.
3. DEO. As above - ADFA, i.e. 3 years. All going well.
I would not reject the ADFA option however the sooner you start, the sooner you finish. Fast jets is a young man's game. Do a degree - ANY degree. It really doesn't matter what you do. It's free, and may stand you in good stead latter on in life.
4. Read this thread!!!