Yes, but let a professional do the job correctly and to code.
Hydralic cement?
no
no
yes with proper knowledge and time
Yes you can!
Only of it light
Many pools have vinyl liners. As the pool ages, the vinyl liner will oftentimes become cracked. These cracks cause water to drain out of the pool, which can result in greater damage. One should never fail to repair this type of leak. The best way to repair this is to patch the crack or hole with a patch kit. These patch kits can be bought both in stores and online. There are different types of patch kits, some of which are meant to be used above water and some below the water. This type of pool repair is relatively simple.
Where to find pool enclosure repair depends on where you are currently. A good way to find pool enclosure repair is to go to google and type in near "your zip code", pool enclosure repair.
With a new pool surface installed- Diamond Brite or any aggregate surface- is it possible or doable to acid wash the pool with water in the pool??
You should remove the antifreeze with a shop vac if possible, antifreeze will not hurt the water, but is just one more thing in the water that you do not need to be there.
a leak
This should be left to the professional pool service tech. He will have the necessary tools and the knowledge of the lighting system and local codes.