There are a number of questions being asked here, and all of them are asking for a person's subjective opinion. Personally, I am against all of these proposals, but that reflects a personal political/social/etc. worldview. I am generally against government of any kind telling people what they can, can't, should, or shouldn't consume. Putting a ban on drinks that are "too large" is a subjective decision to begin with. Who gets to decide what size soda is too large? Additionally, I have problems with a law or regulation that can't be enforced. Let's say that you are trying to prevent people from buying the 40 ounce soda, so all locations that sold it get rid of the 40 ounce size. A person can easily go into that same store and buy two 20 ounce sodas and walk away with the same 40 ounces of soda that the rule is looking to prevent.
The general goal of trying to eliminate these large sizes or putting taxes on things that someone deems "unhealthy" is to try and limit the consumption of these items. Basically, punishments are put in place to dissuade people from unhealthy habits. This is only one type of solution. I think that rewards for healthy decisions is an alternative solution that could be explored. I also think that general education can solve a lot of health concerns. If people are educated on the effects of those drinks on their bodies, they might begin to self-regulate their consumption. Rather than punishing people for their habits, it is a better long-term solution to educate people.