Thank you for reaching out, let us try to assist you.
Regarding your first question and reading what is being discussed in the other thread, I believe setting or not the pull-up resistors from the Edison would make no difference if you’re using a level shifter for this purpose. However, if you want to set them I would suggest you to check the following thread: https://communities.intel.com/thread/106048.
I would personally suggest to use a level shifter, check this link for further information https://communities.intel.com/message/276726#276726, also this video https://www.youtube.com/watch?v=wtithWmd2oE.
Let us know if this makes any difference.