Yes, definitely send through SLS. You will get a number on the receipt to track online, but it seemed to lag.
Sorry, I'm not sure I understand this question.
From previous experience, he knew that the fee paid to CIB was done leading up to the interview (the instructions are actually in the Packet 4 email). I think others contacted the embassy for instructions to pay fees to CIB to include in Packet 3 materials, but we did not.
Hope this helps. It's truly an incredibly confusing process with vague instructions. Hang in there!