I think that #2 makes a number of helpful points if we expand our definition of rationing. Certainly in any system where your healthcare is decided by others it will be "rationed" in that sense, as there are not unlimited funds and tough choices need to be made by companies, doctors etc about what treatment is appropriate and can be justified.
Absolutely -- health care is clearly already rationed in the United States and it cannot help but be rationed in some way. Today, we have two main ways in which our health care is rationed -- we have rationing by insurance companies and rationing on the basis of wealth.
Most of us have health insurance provided by whoever our employer has chosen to provide it. These companies cover things that they (perhaps in consultation with our employers) want to cover and they decide what they will pay for which things. My insurance company, for example, has stopped covering the non-generic form of some drugs. This is, in effect, rationing.
We are also rationed on the basis of what we can afford. Some people can pay for more health care and therefore they get more. Some cannot even pay for health insurance and so they get none. This, too, is a form of rationing.