1) The entire A gates pier will also remain Schengen. I'd assume that your flight would arrive there - although nobody really knows yet.
2) Lounge will be post-security, in Schengen space.
3) For a flight to DEL, even today no secondary security check is required. However, LX does not, and will not, drive you directly to the plane but rather to a private elevator that will take you into the post-security E gates departure level.
4) I believe to remember about 45min before STD.