Yes, but the measurement, the installation of the bead receptor and the in take and return flanges can be difficult. I suggest you get a professional.
by taking the liner away!
No. An underground pool needs strong walls to hold the soil out (when it's empty) and the water in. Usually they are cast concrete.
No
Do a goggle search find above ground pool repair k
To fix a 20 x 40 in-ground liner pool with concrete damage in the deep end, first drain the pool and remove any damaged concrete. Repair the concrete by filling cracks with a suitable concrete patching compound and resurfacing the area if needed to ensure a smooth finish. Once the repairs are complete, allow sufficient curing time before reinstalling the liner and refilling the pool. Consider applying a waterproof sealant to prevent future damage.
Yes it can be done
How are you planning on making the pool water tight? If you want to use a Vinyl Liner, you should consult the dealer you are planning on ordering the liner from. A lot of Vinyl Liner manufactures will not make a liner for that pool.
There are a number of products you can use to prolong the life of your pool. You could install a wall foam between your pool wall and the liner to keep a smooth surface next to your liner to help prevent punctures. You could purchase a liner pad or pool padding for the bottom of your pool. And you can invest in vinyl liner repair kits to repair the small punctures and prolong the life of your liner.
You can get the pool product you need at http://www.cheappoolproducts.com.
If the pool is drained by mistake and the liner has floated, make sure to keep the liner wet. This will prevent it from possible shrinkage.
Yes, its called "Raycrete", its a 2 part epoxy type mix, designed to be used under water. I have used it and it works great. In addition: Depending on the size of the crack, another option is Prattley Putty, its sets as hard as concrete, even under water. and will be easier to use than epoxy. yes, there are many different kinds that can find at dolphin pool stores.
Pool liner repair tape that can be found at most pool supply stores.