1. The Hebrew sentence has a particle gam that adds a particular emphasis on Abel. There is no English equivalent to this particle and is almost always ignored in English translations. NRS, NASB, NKJ & KJV, however, make an attempt at it here with "for his part," "on his part also," and "also" respectively.
2. The firstborn or firstfruit is usually referred to as bekor (singular) and bekkurim (plural, masculine). The feminine plural bekorot used here is only one of four such occurrences (cf., Deut 12:6, 14:23; Neh 10:37 (2x)).