Is it even possible, that in some kind of perfect economy that takes into account all externalities and costs, that there is no need for surplus value to be produced at all - that is, infrastructure and common works are run with costs embedded into the system?

I can't really see that happening without getting rid of money all together.

So yeah, surplus value can be accrued under leftwing governments and used for the public good, but it's not capitalism if it doesn't go to private individuals. Is it considered exploitation if the surplus value goes to providing necessary infrastructure and support for - and under the direction of - the people who created it through direct Soviet style democracy, for example.