Marxism is always open, always critical, always self-critical.
Socialist democracy is not, a luxury and its need is not limited to the most advanced industrial countries.
Revolution is not a goal in itself.
Factions are a sign of illness in a party.
You need a vanguard organization in order to overcome the dangerous potential brought about by the uneven development of class militancy and class consciousness.
For Marx, 'pure' economic theory, that is economic theory which abstracts from a specific social structure, is impossible.