If your door is bad enough to need changing, Weber will replace it at no cost. I still get a little smoke out the door when the fan kicks on, but I don't expect airtight. If you take your time you can shape the door to fit better. I think they all get flattened a bit in shipping, at least the last 4 that I have been a part of putting together.
Bottom grate is generally 4-10 degrees different than top rack and it will vary depending on whether you use a foiled pan, foiled with heat sink, or foiled with water in pan.
Smooth Smoke BBQ Team, KCBS CBJ, 2-WSM, Cajun Bandit Conversion, wsm 2880, Smokey Joe Mini wsm, Old Country offset, several kettles.