I'll answer some of that with what I've learned so far.
1) Most officers will be assigned different jobs depending on where you're stationed. It's based on what's needed. You definitely get to say what you want to do, and for a non-rated position you'll likely get it. It's just that every so often you may be restationed and have additional or different duties (I've been told this is managerial type jobs). Officers get much higher pay as well.
2) I believe enlisted is 4 in minimum. Officers vary, I think the minimum may be 6 years. What I've learned is that pilots who don't want to go career will leave after their 10 minimum because after that time you get less flight opportunities and mainly go to a desk job.
4) Stipends vary for enlisted and officers. Subsistence money (food) is $350/month for enlisted, $230 for officers. Housing allowance rates are based on rank and family size, so an E1 would have something like $400/month and an officer with a family of 3 in later years could get something like $1000. Your salary is taxed less. You can shop on-base at the PX where goods are at reduced prices. There are various plans for investing your money during a tour and for retirement. For critically needed language skills, such as Mandarin, Dari, Arabic, you can get up to $12,000/year for active duty members; this varies by your proficiency and other factors.
5) Yes, you can get training as an officer for the reserves. Bear in mind, you must be an officer to fly.
6) Pretty close to a regular desk job, just on base or somewhere secure.