Okay... well, here I am, although I noticed from the 80s slouch boot question on the member's board that there are other shoe experts around here too!
First of all a split leather means that the cowhide has been split into two full hides, resulting in a hide with a smooth finish and a suede opposite side and another complete hide with two sueded sides. This is a way to create a more supple leather, something that is still strong, but not as thick as a full hide. The sock is the proper shoemaker's term for what many refer to as the insole. The sock is a cosmetic addition placed on the inside of the sole, often just glued down over the insole and sometimes printed with the maker's name. That type of sole is called a stitchdown sole - not suitable for wear outside where dampness can travel through the stitches, but fine for indoor wear, which is why you often see this type of construction on bowling shoes and slippers.
As for a date, I think Hollis is correct. This is a later example of a 40s style shoe, and I think quite late, probably early 1970s.