What is the worse that can happen?

I have a pool that has suffered from my lack of knowledge. I would like to get unbiased opinions on whether I need to take quick action to resolve the problems or can wait.

I have an in ground gunnite pool about 22 years old. It has a grey stone coping, with two rows of 4x4 tile above the plaster surface. It also has an automatic cover. The pool is at a weekend home so I am not around to perform maintenance during the week. About ten or 11 years ago had the pool drained and refinished after the tile fell off and the coping deteriorated. It has gotten to a similar state again. The top row of tile has largely fallen off, the lower row is still largely intact. I was recently informed that the coping needs periodic re-grouting, something I was never advised of in the preceding 20 years. I was told that water penetrates behind the coping and enters the pool at the tile level, causing the tile to loosen and fall into the pool. The recommended solution is to drain the pool, R&R the coping and tile, and do better maintenance going forward. This amounts to nearly the same thing as the complete refinishing I did a decade ago.

My questions:

1) If I put this costly operation off for a couple of years, will I do serious damage to the pool? I.e, does the absence of tile allow the water to penetrate lower, behind the plaster finish, and cause serious damage? So far, the plaster looks fine.

2) Is it worth doing just the upper work after ten years or should I bite the bullet and refinish the whole pool?

3) Is tile necessary or are the other finishes for the top level of the pool? I assume the plaster coating cannot extend beyond the water line.