Who are the two ladies in Major Kusanagi's apartment?
They're the Major's friends/friends-with-benefits. (She actually does have a life outside work.) The one with darker hair is named Ran; the one with lighter hair is Kurutan. She isn't a maid bot, she's just wearing a frilly dress and getting Motoko drinks, well, 'cause... (By the way, I think it's actually Kurutan's apartment -- the Major was borrowing her virtual reality equipment to review the case.)

Kurutan is actually also featured in episode 8: She works as a nurse, and the organ trafficking case involves two of her patients. She calls in the Major and Section 9 after the police investigation founders.

I haven't read the manga, but I understand that it features more of Motoko's relationships. Apparently she had a boyfriend (who made one cameo in SAC), and she had a virtual threesome with Kurutan and Ran, as opposed to their more implied relationship here.

I don't know more about them. Still, with their names, you should be able to find some more on Google.

(References: TV Tropes, Wikia, and the credits.)