I'm new to this home automation and find myself in the middle of a remodel of my ranch home that consists of a foyer with stairs that go up and down with a 6" recessed can above the foyer, and a 4" recessed can at the top of the steps. These have a single switch at the top of the steps (3 way) and at the entrance to the foyer in a 2 gang box that also has a switch for the outside lighting. I will have 4 recessed cans in the living room to provide overhead lighting with a ceiling fan in the center of the room. At the entrance going back the hallway from the living room currently is a single switch that I want to convert to a 3 gang box, with one switch that controls the 4 6" cans in the living room, another switch to control the ceiling fan that has no light in the living room (that will also control the fan speed), and a 3rd switch (3way) to control the 2 4" recessed cans that I have placed in the hall way leading back to the bedrooms with a switch on the other end of the hallway to control the hallways lighting. I'm only remodeling one bedroom currently that also has a half bath. I will be adding 4 6" recessed cans in the bedroom with a ceiling fan that has no light. There will be a 2 gang box with one switch to control the lighting and one switch to control the fan (that will also control the fan speed). I will have one 4" recessed can in the half bathroom that will also provide power to the light over the vanity off a single switch in the bathroom.

A few notes:

1) I do not want the lighting in the bathroom or the outside lights to dim.
2) The lighting in the bathroom should be 5000k, Foyer / Stairs, Living room and hallway 3500k, and bedroom 2700k.
3) I want everything to be controlled by Alexa and my iPhone with dimmer a dimmer preset available in the living room and bedroom at a minimum. Also to assist with interacting with my Ecobee 4 if possible.
4) I want to use LED Retrofits but have not selected the bulbs yet as I am unsure what to use since I don't know what switches to get yet.
5) Ideally if possible I would like the lights to go from 100% to OFF through the use of the dimmer.
6) Which hub would be the right hub for me?

Any help would be appreciated. I'm a bit overwhelmed and not sure what I should be buying to be honest. Thank you.