Yes, it just depends on what kind of sand it is
Nothing if its a sand filter However if sand is coming into the pool from the filter then you may have to replace one ore more laterals in the sand filter as they have worn and are letting sand through to the pool,
If you have a sand filter the laterals in it may be starting to show signs of wear these wil blow sand from the sand filter into the pool when they wear out.
It could damage the internal PVC of the filter and cause sand to get in your pool.
The sand filter wont make a pool green this happens a s a result of algae.
If you are getting sand coming into the pool and have a sand filter you may have to replace worn laterals in the sand filter.
No.
Your filter will tell you on the side of it how much media sand to put in it.
One of the lateral returns inside of your sand filter may have snapped. When that happens, it can send sand out of your returns. Have your local pool place repair your sand filter.
Yes
A good way for getting sand out of a sand filter is to get a sand venturi with this attached to the end of a garden hose you will be able to suck all of the sand out of the unit easily. Check with your pool shop as they may be able to sell, hire or lend one to you.
There should be a drain plug near the bottom of the filter. Open it and let drain. The sand will stay in.
Probably not going to be adequate.