Looking for a general Marxist view on Freud.

At first glance, to me everything relating to Freud sounds like pseudoscientific, idealist garbage ... everything that Marx's scientific socialism should be opposed to in principle. Nevertheless there was a Freudo-Marxist school that overlapped with the Frankfurt School, who thought the ideas of Freud and Marx could be married to some extent.

So,

1. What was Freud about?
2. Was Freud full of shit?
3. Is Marxism compatible with psychoanalysis?