What worked for me was using four large binder clips for the little amount of leakage, 3/6/9/12 o'clock I had miniscule smoke coming from the lid/bowl seal on a nearly new China made LE whilst using the SNS.
Just following the instructions they give I set it and forgot about it for about 8+ hours and could have gone another 1-2 more easily.
For searing it depends on what you're cooking, fire up 30-40 new coals and sear it up.
You gotta remember we're not building cabinets here we are just making a meal so no need for perfection.
Have fun and enjoy cooking on your Weber you will find out what works best for you.