For the second part of your question…….
These are taken from the community noise document. Based on ISA, All Engines and max structural takeoff weight the following climb gradients should be available at 1000 feet.
B747-400, 10% climb gradient at takeoff power, reducing to 6.5% at climb power.
B777-200, 13.8% climb gradient at takeoff power, reducing to 8.5% at climb power
B757-200, 14.5% climb gradient at takeoff power, reducing to 10% at climb power
The newer B737 aircraft should have similar gradients to the 757/777.
Mutt..