Yes, choices will add up to you getting either the "human" or "monster" ending. Additionally there is a choice gate to not pursue sex.
Yes, right now I'm planning on about 6-8 cgs per character route in the main game. Most of them will be explicit/fully 18+ with a mix of both monster and human forms, though there will also be some non-explicit cgs of important story moments too.
Mori will be getting 18+ cgs in the future, and Amir's intro (now in early access / will be public in a few months) does have an explicit cg. :)