Yes, you can below are the definitions. 1.weighting is a value which is given to something according to how important or significant it is. 2. If something is given a particular weight, it is given a particular value according to how important or significant it is

No, "weights" would not be acceptable here. "Weighting" is being used as a noun here. In this context, it would mean the practice of giving increased value or importance to a particular item. "Weights," as a noun, would refer to things that you lift. Also, I think that you were asking about the placement of the phrase "in the series"? Prepositional phrases can sometimes be moved to several locations in a sentence. In this case, however, moving the phrase would change the meaning. "...of the items in the series it selects for its consideration" gives the idea of selecting a series and considering that series. "...of the items it selects for its consideration in the series" gives the idea of selecting which items to include in the series. Hope this helps!