So many things with no explanation

It seems that the film put elements just to cause shock without any explanation:
1) Why the lost man have a deformed arm?
2) Why Lenon shoot Mrs. Finley?
3) Why Mr. Finley eat Mrs. Finley's guts?
4) Why the missing people always leave a shoe?
5) Why Lenon's mother was eating her fingers?
6) What did it mean when Zhang says: "They take but we don't do anything" and then she points into space, what is she talking about? About aliens??

It could have been a good movie but it is very slow with things without explanation