LE CREUSETEnameled Cast-Iron 7-1/4-Quart Round French Oven,

I have had this pot for several years. Is it only the knob that can’t withstand heat greater than 350 degrees?

how many pounds does this hold?

My first Le Creuset purchase--a 6 3/4 qt oval french, but i notice the lid doesn't sit just right and steam escapes. Will this matter?

Had this pot for yrs and the bottom has become black, all the enamel gone. everything sticks. what do i do? should i contact le creuset?