how many uncles can one block include? I think I read somewhere that you can only include maximum 2 uncles, is that true? If a block includes 2 uncles or more, how is the reward distributed between those? If one uncle gets 7/8 of the static reward, the 7/8 is distributed between multiple uncles?
One block can include up to two uncles. If a block references two uncles, each uncle will earn 7/8th of 5 ETH to whoever mined that uncle. Each uncle being referenced will also earn a small reward per uncle (1/32 of 5 ETH) to the miner who references the uncles in his / her block.
You can find more details here in the Rewards Mining section.