1) Your current membership card (assuming you are already a Silver) will be valid until the end of October anyway. You'll be OK for lounge access for your flight this week.

2) Flights are posting unusually slowly at the moment. My bet is that it will auto-post sometime soon. It's likely to be adjusted and your membership will be upgraded without intervention sometime (maybe 3 days or so) after your TPs have posted. If that doesn't happen in the next 10 days, then call. I wouldn't even bother calling right now as there seems to be a system-wide slowness to post TPs/Avios (my own flights included).

3) If you are not already Silver, then there is probably nothing you can do for your flight in Y this week in terms of lounge access, unless your flight posts in the meantime. If your flight does post, then your status may well be upgraded in time.