Did I read correctly that it only needs 2 PCI-e cables connected to run as normal (not overclocked)?
Correct. 2 for regular, 4 for OC'ing.
What I do not understand is this sentence: "Dont parallel connected different DC input from different PSU into the same Hashing board." So does this mean you need two PSU if you're overclocking?
I would think the opposite just use 1 psu with 4 pcie cords not 2 psu each with 2 cords. best to be careful let some one else be the first tester of that