I'm gonna guess you were educated in a rockerfella skool, huh?

Murderers absolutely have to be stopped,

Yes.
Stopping murderers is self defense and not a violation of the non-aggression principle.
Ergo, stopping the taxman from collecting through non-voluntary means is an equally justifiable use of force and for the same reason.

If your utopia requires armed thugs to persist, it sucks.
(An armed population using force to defend itself against those that would rule over them through the use of force is not an interchangeable equivalent.)

But, at what line does one become a Nanny State?

I want a nanny state.
Instead of the bs skooling we get now, a proper management system would have a set up that precludes homelessness, unemployment and poverty, rather than encouraging it as means to stay in power.

What is your plan for when the communists run out of food (inevitability) and they come over to the capitalism group to steal food?

You presume too much.
I'm gonna blame your rockafella education, again.

https://theanarchistlibrary.org/library/petr-kropotkin-the-conquest-of-bread
Why would we run out of food when growing food contributes to your social minimum?
Lots of people helping other people to succeed is what communism is all about, despite any contrarian views held by those that do rule over others through violent means.

IF you want to put the crapitalism question to rest between us, follow this link and show me where the math
of chapter 9 is wrong.
You could read the whole book, but much of it is fluff to make it salable to a broader audience when it was published.

In a sound money environment much of this argument becomes academic, imo.
The crapitalusts have a harder time stealing your labor when they can't inflate the monetary supply.
They have to do it the old fashioned way by sending out the thugs and exposing the iron heel.
Folks eventually push back on that, and the violent rulers know it.
Ergo, it is much better to shrink the language, train the slaves never to read, and allow them to falsely think themselves free and ruled by 'the greatest system eva!'.

To sum up, using violence to attain your political goals makes you a terrorist and fair game for any killers out there wanting to clean up the gene pool, imo.
If you have to force people to obey, your ideas suck.

I can lead you to the knowledge that finally led me out of the ignorance installed by my own rockafella edumacations, but I can't read it for you.
You would have to do that.

This is the book that lays out the foundation for anarchism:
https://theanarchistlibrary.org/library/pierre-joseph-proudhon-what-is-property-an-inquiry-into-the-principle-of-right-and-of-governmen.

These two books outline what a more cooperative world could look like:
https://www.abelard.org/e-f-russell.php
https://archive.org/details/lookingbackward01bellgoog

These two books lay it out the math academically:
https://theanarchistlibrary.org/library/petr-kropotkin-anarchist-communism-its-basis-and-principles
https://theanarchistlibrary.org/library/petr-kropotkin-mutual-aid-a-factor-of-evolution

This one does it in more workaday language:
https://theanarchistlibrary.org/library/alexander-berkman-what-is-communist-anarchism

This one lays bare the name stealing that is victimizing all rockerfeller indoctrination victims:
https://theanarchistlibrary.org/library/emma-goldman-there-is-no-communism-in-russia.

So, as you can see, I don't come to my conclusions lightly, nor from inculcated indoctrinations, I did the reading for myself so that I could know a better version of the truth than I was given by those that had ulterior motives to what they called 'education' and I call indoctrination.