1. You're overthinking this. Stop. It's fine.
2 & 3. It the plugs threaded out and back in fine, the threads are fine. Stop looking for problems that aren't there.
4. Torque spec allows up to 22 ft/lbs. Reduce that by 20% for the anti-seize and you're at 17.6 ft/lbs. You're at 18 ft/lbs. They're fine.
If anyone comes along and points out the inaccuracies of torque wrenches, just ignore it. If anyone says "you shouldn't put anti-seize on spark plugs", just ignore it.
2 & 3. It the plugs threaded out and back in fine, the threads are fine. Stop looking for problems that aren't there.
4. Torque spec allows up to 22 ft/lbs. Reduce that by 20% for the anti-seize and you're at 17.6 ft/lbs. You're at 18 ft/lbs. They're fine.
If anyone comes along and points out the inaccuracies of torque wrenches, just ignore it. If anyone says "you shouldn't put anti-seize on spark plugs", just ignore it.