toilet installation

I need some help on the best way to install a new toilet. I have included a picture below with the parts labeled. I installed a new sub-floor and a Ditra membrane (orange) around the pre-exisiting 4" ABS pipe. Now I need to install the flanges. Here are the questions.
(1) The ABS pipe seems very sturdy and rigid but its sealing surface is not parallel with the floor. It is nearly 1/4" higher on one side than the other. I guess the wax ring that I removed from the old toilet made a seal since it didn't leak over more than 20 years. Should I put the red shim (picture) on one side to help distribute the weight? If I do use the partial shim, should I use an elastomeric caulking, plaster or what?
(2) I laid out the parts in the photo in the order that I would use them. The tile is 3/8" thick.
(a) The order of the parts starting from the subfloor are: split metal ring, shim (if used), wax ring, white plastic flange with a grooved red rubber seal that goes inside the 4" pipe and the another wax ring between the flange and toilet.
(b) with all of the components except the uncompressed wax ring between the toilet and flange, the top of the flange is at least 1/2" above the plane of the tile. By the time the second wax ring goes on, the final assembly will be 1-1.5" above the tile. Is this too high? How much can the wax rings be compressed?
(c) since it appears though the gas tight seal from the flange to the ABS pipe is made by the grooved read rubber seal on the flange, can I get away with a foam gasket, caulking or something else in place of the wax ring between the ABS pipe and flange?

Please help me decide the best installation plan and thanks in advance for your help!

 

I am thoroughly confused by your description and pictures. You talk about ABS piping but you show a PVC flange utilizing a rubber seal. You talk about the existing flange not being parallel to the floor, the original wax seal not leaking and then about adding shims (where?) to distribute the weight.

First things first. Generally speaking ABS is NOT compatible with PVC. That rubber seal may be an exception.

Second, the toilet flange is intended to be mounted ON TOP of the finished floor, screwed solidly to the subfloor. When so mounted the flange will be parallel to the floor and the toilet will set solidly on the floor. The wax gasket of standard thickness will properly seal the toilet to the flange.

I have no idea of what you are trying to illustrate with the tower of flange adapters, shims and two wax gaskets.

 

It looks like you have too much stuff. Usually the toilet flange is glued onto the pipe but the slip in kind like you have can be used. Usually the flange sits on top of the subfloor though if your tile is theck enough it can go on top of your tile backer board. Then the wax ring goes on top of the toilet flange and the toilet gets placed on top.