contact the manufacturer. If manufacturer is unavailable, you may be out of luck.
You have no choice but to replace the liner
I always cleaned off the ground. Then I covered the area with sand. People will walk across the bottom of the pool in bare feet. You want it to be comfortable for them and you do not want the bottom of the pool to rip.
Yes, pool companies sell "Under Water Cement" and patch kits. If you hole is bigger than the usual patch, ask the pool company to sell you a piece of used liner.
if you google - installing an above ground pool - you will get links to sites that post quite explicit directions good luck
Masonry Sand is used to level the bottom of a pool
Yes, but use a ground cloth. It protects the bottom side of your liner.
Buy a pool patch
The cost of an above ground pool is relative to what you want IN a pool and what you want with the pool...............Accessories.