OPK Qs

I'm new to the OPKs and have a few questions…
1. Does that LH surge mean that you are ovulating OR will ovulate within 12 to 24 hours?
2. When there is no LH surge (after you've had it), does that mean the egg has already been released?
3. If I had sex the day before and the day of the LH surge, should I still try to have sex once the smiley face is gone?