I too got a mail from CX for the stage 2. I had my interview on the 20th feb. I had a word with Mr SS on that day regarding the whole interview process and asked about when would be stage 2. He said not sure of dates but should be around April end or even sometime in May.
And regarding the ECR/ECNR stamp on passport (irrelevant now), here s the link-
Emigration Check Not Required(ECNR) Stamp
Visa on arrival is granted if the stay is for less than 14 days. Here is the link-
Requirements for Indian Nationals to apply for Hong kong Visa