"if a mulatto ", the child his maid was expecting was to receive £100 or 3 slaves. (Have I got that right?) It seems to me that he thought the child might be his. If it wasn't a mulatto he would assume it had been fathered by a slave.
I agree with Greensleeves that the mulatto (James?) may have been his son or another relative. He was to be educated until he was 15 and receive a large sum of money in addition.
I can't decipher 2nd extract apart from some of names, Silvia, Polly, Agnes.