Yes the idea is to make a version between MGSV and Metal Gear 2: Solid Snake. The most iconic look of Big Boss is the one seen at the end of MGS4 with his long brown coat. Ironically, before MGS4, we had only seen that look through MGS1 artwork of Big Boss. And that's basically how most fans captured old Big Boss visually, so it was a huge surprise to finally see him "in the flesh" with this outfit at the end of MGS4. Under his coat, he wears a suit with a tie, like he's about to go to the office. I don't have those kind of clothes for 1/12, and it has never made much sense to me that he would wear this kind of suit, he looks like a retired soldier when in reality, he fought all his life.
So I decided to do something else.
I want to capture this iconic look (hence the upcoming coat) and at the same time have him ready for battle under his coat. With gear he wears from MGS3 till Metal Gear 2: Solid Snake.
I may do a variant in the future with a green military suit and red beret.
I suppose he should wear both Diamond Dogs and Foxhound patches on his "final" coat because those represent his two last teams. If you notice in Peace Walker & Ground Zeroes, he wears both the Fox logo (his previous team in Portable Ops) and the Militaires Sans Frontières logo (his current team). In The Phantom Pain, Venom wears both the Militaires Sans Frontières patch (previous team) and Diamond Dogs patch (current team). Then Big Boss takes command of Foxhound.
As for who he is: both (hence the tail and the absence of horn and scars). Because to me, Big Boss suffers from schizophrenia in The Phantom Pain. Some fans choose to believe there are two Big Boss at the end of MGSV because that's what the game tells you literally, but in my interpretation, if you listen to the Truth Tapes, they don't add up to the facts. In the book 1984, Truth=Lie. So fans should be very cautious and take those final tapes for what they are: interpretations and probably misleading. There are a lot of things that don't add up in the game, overall. The Paz final cutscene explains everything, in my opinion. The trauma Big Boss suffered and his denial to face reality.