Yes by putting an even layer of sand down you will protect the liner from the irregularity's in the ground and absorb impact from above.
Definitely, If you don you will wreck the liner
YES
Sand is normally put under the pool liner to create a smoother surface.
I just put up an above ground pool and we used sand to level the ground. To level the sand, we used one of those string levelers and tied it to stakes on each side of the pool area to make sure it was all level.
It could damage the internal PVC of the filter and cause sand to get in your pool.
Unfortunately, no. If the sand isn't level when you put the pool on top of it, the bottom of the pool will stay uneven after it's filled. Sorry.
You don't use sand to level the ground that the pool sits on. The sand is used on the inside of the pool, after the ground has been leveled by taking the highest point down to the lowest point after the grass has been removed. The manufacturer's usually recommend 2" of sand on the inside of the pool before the liner is installed. It sounds like you are installing a used pool, since you do not have instructions. Here is a link to some instructions that could possibly be used. http://www.royalswimmingpools.com/install.htm
Your filter will tell you on the side of it how much media sand to put in it.
Washed float sand.
Well, first you lift up the mobile home. Then, you put the sand under it.
Its not a good idea to put a plastic liner under the pool. It retains moisture and rots the walls and the rail the wall is in. Your pool will not last. If you follow manufactures instructions, sand under pool and a good drainage system around the pool will make the pool last 25 years or more. Whenever water sits against the pool walls its going to eventually rot the wall and can seep under pool causing the sand to shift and then the liner will go bad.Its all sales hype about the coving and gorilla stuff...its not needed.
That'll depend on the size of the pool.
you can but it would be best to put a layer of sand under the liner to protect it from the hard cement. Otherwise you may end up with a damaged liner.