flight level in Flight simulator

Hi!

I have three questions about fling in FS.

1. what does it mean when ATC says. climb at FL290, for example. what
height is it?

2. when ATC said that I have do climb to 11,000 and reached that level
ATC said that I`m 2000m above my flight level. Internationa settings
are set to metres. but also if I set the settings to feets the numbers
were not coresponding.

3. what should I do whet ATIS or ATC says, i do not know exactly,
something about the pressure or height on target airport.

Thanks in advance
Robert