Shower pan, flange or no flange? Mud or foam?

Hello- I am installing a shower in my master bath. It is my first time working with tile, thinset, mortar, cement board, any if it. I am trying to decide if I am going to go with a custom shower pan or build it myself (it is not a standard size).

Question 1- are the pre manufactured foam floor slopes really just as good as doing it with mortar or are they just easier and more expensive?

Question 2- I am trying to decide between using the Kerdi $ystem or having a custom basin made by KBRS. Any recommendations.

Question 3- KBRS makes a full tile pan which is ready to be tiled for about $700, or they will make just a custom floor slope for about $450 in the dimensions that I need. Which is a better method, to put down the floor slope and bring the cement board down on top of it into the sealer, or to use the tile basin with the flange and float the cement board over the flange without making contact, per instructions. Or a third option, tile-redi had a sort of Z-flashing, I could set the cement board on too of the flange and use the flashing. Any comments?

Question 4- any advice on where to get or what to pay for good shower doors? We want frameless, 1/4" or 3/8" hinging doors with a neo angle. Sides are custom to fit with walls.

Thanks, I appreciate (in advance) your response.

Shower pan, flange or no flange? Mud or foam?