THis may be really stupid, but what is a health unit coordinator? Maybe I just read it wrong, but I can't come up with anything!
I used to be a UC. Here's my best answers to your questions:
1) It depends on the facility. I have experience with two large health systems, and at my current job, the UC duties are as follows: They Stuff charts, answer phones, enter orders written by physicians on paper into the computer, scan med orders to pharmacy, print workshets for RNs each shift, and any misc. duties we ask for (example: getting blood from the blood bank or running labs downstairs). We have a few UCs who are not crosstrained, maening that they do NO pt care. They are not even supposed to help with boosts. But they will answer lights and find someone to do whatever it is the pt wants if they can't handle it themselves. The crosstrained ones help with pt care as time permits as well.
The other system has physician order entry, so those UCs are a bit different. They are still "gatekeepers" if you will, but they answer phones, answer all call lights and page the appropriate person, check the computer for new orders and make sure the RNs are aware and have all the paperwork that they need (eg contnt forms, etc). They do a lot more than that but I never worked as a UC there and it has been awhile since I have been there, so I can't remember any more specifics.
2) The above answer kind of answers this one too. As environments chagne, roles change, but it seems that most places still use UCs.
3) I suppose that varies as well. Where I work now, and I believe at the other place, they need to have a high school diploma, and then they get "on-the-job" training. They usually prefer experience, either in the field (eg someone was a tech and then got trained as a UC, hence what I said before about being crosstrained) or some kind of secretarial or medical background. My unit hires mostly nursing students and techs as UCs.
Hope that helps!