Okay, sort intro: I only started baking bread about 3 weeks ago, I've been trying to find a good brioche burger bun, so far I've done the bun Heston uses in his perfect burger [1]. I went into this blind, no knowledge about the science behind the yeast, flour etc... I put in too much yeast into this and it tasted pretty bad, texture was good though, but too many ingredients for my liking. I then tried a brioche bun recipe incorporating the tangzhong method. I cant find that recipe right now, but it was moderately successful, I felt that it wasn't buttery enough. I had another attempt to modify a brioche recipe but it turned out to be a disaster, not much learnt other than I shouldn't modify things too much if I dont have a clear understanding of things.

This is my latest attempt, I used Thomas Keller's brioche recipe [2]: It tastes a little more like a buttery pound cake than bread, I believe this is due to the amount of cake flour in the recipe(2.5 cups cake flour and 2 cups AP), my sister says it's because the bread was overproofed

I have a couple of questions:

1) Is the bread supposed to be this texture? Is it this texture due to the cake flour or over rising the dough?

2) Did the bread crack because I didn't score the top?

3) Whats a good brioche recipe I should attempt if burger buns are my end game?

4) For the first rise, I usually rise it in an air conditioned room(23C) for about an hour, punch/fold&press down, rise a second time in the fridge overnight, shape the dough, either into rolls or in a loaf pan, then cover and rise for 6 to 8 more hours in the fridge. My question here is, can you basically rise(2nd and 3rd rise) dough in the fridge for extended periods of time(8-12h)? Will this cause the dough to be over proofed?

5) Can the fat% of a recipe, or the fat to flour ratio be varied? If I find a dough not buttery enough, can I simply add in more butter? How do I know that the dough will be able to hold in the fat?

6) Is this tangzhong method worth pursuing? I understand that it gives bread volume and longer shelf life, but I can't seem to find a reliable way to modify regular recipes to incorporate the Tangzhong method, since the method introduces quite a lot of liquid into the dough

7) Do all aerated(?) breads benefit from bread improver? Why don't I see more recipes using this since it seems like there are many benefits to  use this

8) Is there a way to tell if you have over kneaded the dough?

Appreciate any helps/replies