Andy, I have no problem sharing what I know to help the members here! I responded to this this afternoon, one of my typical long- winded posts, but somehow it didn't get posted (probably my fault, I must have hit preview instead of submit ) Oh well, look at the bright side, I can boil it down and just give the info without so much rambling/ disorganization (if I boil it down too much, just ask for a little more info on anything I say)

1/4 - 1/2" should be good for the shallow end, remember that the floor is probably not level, try to shoot for that amount under the average depth.

Grecian hopper means you have 6 points to establish to make the hopper floor. Keep the edges of the hopper floor parallel to the side/ back walls - it'll make the liner easier to make and fit into the pool. Because the sand has a tendency to 'disappear' over time, you might want to expand the floor of the hopper and use some of the extra to fill in where you will probably run short on sand at the bottom of the slope/ hopper walls - if by some chance you end up with some extra sand by doing this; it's easier to haul a few buckets of sand out of the pool than top have to run out and get more or try to blend into the voids! If you have a MD, that's going to have to be the level of the floor.
Remove any stones you find while troweling!!!!!!
The wall measurements should be sent to them exact, they will do the undercut so it fits correctly. Also send them both sets of diagonals (side walls and end walls), cause many installers have trouble properly squaring up a Grecian pool.
While the pool is draining you can watch the water level on the floor, slope and walls to see large humps and voids.
Right now the concern is measuring the pool properly, but keeping some of this stuff in mind will lessen having to pull a bunch of material out or bring a ton+ of sand in and apply it - when the time comes to string out the pool and retrowel the bottom, I'll give more advice as needed
I STRONGLY advise procuring new gaskets for the skimmer(s), light(?) and MD(?) and new faceplates for everything (& screws if needed) - a new liner just looks better with new faceplates and shiny screws.
Do you have stairs that the liner goes over? - if so you've got to send them the EXACT stair dimensions so that you don't end up with wrinkles.

That's about what I can remember from my 'lost' post - if I think of anything I neglected I'll add it - if you need me to expound or clarify on anything, just ask