#2 depends very much on what you mean by "Communism". If you mean "Marx's prediction of what would naturally evolve to replace capitalism [0], and what flaws in capitalism would produce the discontents that would provoke that change", then so far it hasn't been particularly wrong, though the developed world has only, so far, progressed in that direction so far as a system which implements a limited form of socialism over a property-rights system which follows that of capitalism in broad outlines, with key exceptions with major effects.
If you mean the program that Marx and various others advocated as the best means to facilitate and realize that transition, making it immediately real (or at least, transitioning fully to its socialist phase) in his time, well, while people advocated for that, the program was never adopted in any of the states where it was advocated, so it can hardly be called a "technology" (to the extent that it was a kind of social technology) that failed, so much as one that no one ever bothered to give a trial to.
If, instead of either of those, you mean the radical rejection of many of the key principles (including both in preconditions and mechanisms) of Marx's Communism represented by Leninist vanguardism and its various derivatives (Stalinism, Maoism, etc.), yeah, that failed rather spectacularly.
[0] the "capitalism" for which the term was coined, the economic system of much of the developed world in the 19th Century, which is very different from the system which exists now that sometimes is called "capitalism".