Why Dictators Go Mad

Hi,
THis last year has been one of the most satisfying in my career. For those who don't know, I am a Radiographer, we are the guys and girls that make the pretty pictures so the nice people in blue pajamas can fix you, and stop you dying. Scans, x-rays and stuff.
Well, this last year has seen me go from shop floor to acting up in charge.This has been nice, and a long time coming, and I am not complaining, oh no.
But there have been some things I haven't got my head around yet..
Like, why do people think it is acceptable to give me advice, well meaning no doubt, but quite forcefully in the middle of the staffroom, where I can't reply without being unprofessional? .
And why do people ask me a question whilst I am eating? Am I not allowed to eat?
I also can't get used to being observed, every time I do something, all eyes are on me, watching for the signs that I am either a megalomaniac in waiting or am unable to make to jump to charge.
Oh and that's one of the great little pearls of wisdom I have been told, (whilst drinking my tea and trying to have a break from the job) You have to grow into the role of manager, but don't change...
How??? What do they want from me!!!
It's enough to make me scream, honestly! I didn't ask for this, I was asked!
It seems my fellow workers have overnight adopted the get-your-retaliation-in-first attitude, and that they expect me to become this distant dictator figure, someone they can all hate, the enemy.
That hurts, honestly I have always gone out of my way to help anyone I can, and I rarely ask for a favour in return. I though that people might remember who I was, but some haven't it appears.
So now I have experienced this side of them, I don't really know if I would feel comfortable rejoining them as a co worker. Which is really sad, as I like my job.
So if I don't get the permanent charge job, then I will have to think about what I want from my career, and from my working life.
I have learned a lot in the 3 weeks I have been doing this, and once you learn something, you can't really un learn it, can you?
Ah Well...
Be Good, and have a happy New Year