1 and 4) if possible you would use an acf/fields/relationship/query filter. However, I do not now if changing orrderby or posts_per_page will have any effect. Some of the arguments are not changeable. If changing these arguments does not work then contact the developers.
2) Contact the developers for feature requests.
3) Yes, there are filters and functions that would let you do this. You’ll need to give more details about what you are trying to accomplish.
