Sprung Swing Up Flap Hinge Set 2 x 180N Zinc Plated

Hi I have a catering van and I need a hinge that will allow me to to flip the serving shelf from inside to outside so rotate say 275 degrees. What do

Do the hinges open to full 90 degree angle or is angle less than 90 degrees?

Can they be turned upside down to make it a downward opening?

Can we use this for folding table? What max weight can hinge hold?