I'm somewhat new to Marxism as a whole, and do align myself relatively passionately with many of its key ideas, but several fallacies stand out directly to me in that stand in the way of embracing the ideology to its full extent (especially from a practical standpoint). I understand what you're stating when you conclude that:

"States will exist as long as classes exist, and will wither away only > when there is no opposing class to suppress." My question to this is, to what extent and how long would it take to fully enact this suppression of opposing class? By what means would it require? Obviously the class is a compilation of the bourgeoisie, but what definitively outlines the nature of an individual of the proletariat as opposed to the upper class, and who has the authority to make that distinction? What I'm trying to hit at is essentially how to you prevent the loss of innocents due to "political reeducation" seen for example in places like South Vietnam, where masses of people (such as the Catholic population in the country) were eliminated as a result of this violent overthrow and introduction into a communist society.
Also, assuming that division is defined and the suppression enacted, I was somewhat confused about to what extent you meant by: As long as the remnants of the bourgeoisie exist anywhere, the >continued existence of a strong proletarian state is perfectly in line >with Marxist thinking? I understand that one of the base principles for Marxism itself is the revolutionary restructuring of society from capitalism to socialism and the toppling of a society ruled by an elite class, but would this proletarian state stand in power until bourgeoisie throughout the domestic nation were removed, or until the world as a whole was deposed of it? This latter option seems impractical in a sense, as to systematically revolutionize all of society into proletariat states seems to me to promote radical totalitarianism, as both the Soviet Union and communist China ruled as totalitarian states and remained oppressive in nature throughout their revolutionary process and into their establishment of a long term government.