Replacing I/G 20x40 vinyl liner

[church20x40]

This pool was originally installed in 1970 , has 2 return lines and 2 skimmers, the walls are steel and the bottom sand.
We had the liner replaced about 12years ago, and the company that did it said we didn't really need a main drain, so they removed it. After 12 years of cleaning and researching i think that may have been an mistake, and since we are replacing the liner would putting in a main drain be a good idea ? . I have heard of diverters(eyeballs) that screw into the return lines and the water diverted to the bottom to keep debris moving and circulating so it can get to the skimmers and get filtered out. We plan on doing the work ourselfs, just looking for some guidance/advice to make sure we get done what needs or should be done. We are also going to an automatic cleaner this year, no definite decision yet but looking at polaris 360. The place where we bought the liner from recomended going with diverters(eyeballs) and the polaris as an alternative to putting in a main drain.

I'v seen wall pading for the sides, and was wondering if the same could be used on the bottom also. i think it would give the bottom a nice soft feel.

thanks much