A: I typically and most often use Procreate for my final illustrations and sketches. However, I also sometimes draw a draft on some loose leaf paper or a junk notebook if I don't feel like staring at a screen (it's fairly rare though, unless it really is just a doodle). If I wanna be different I might use Clip Studio Paint or IbisPaintX or the Apple notes app but I don't do illustrations on there anymore.
A: I am genuinely so sorry because I have SO SO many brushes that I rotate between. If I had to choose just a couple (which tends to be what happens anyways for hot minutes) I would say a lowered opacity pixel brush (I literally can't find the link to it because the brush name is in Korean) or any default soft pencil brush for the sketch, slightly blurry technical pen for the eraser, and a flat brush or the deyq rendering brush for, well, rendering. If it's traditional, I'll just be using any mechanical pencil I can find (those are more comfortable than wooden pencils for some reason). I'll also be using highlighters to color.
A: I use a 12.6 inch 5th Gen iPad Pro with the Apple Pencil 2! I have a no name matte screen protector and I also sometimes use my 8BitDo Micro for Procreate shortcuts. If I'm on my laptop (Acer Nitro 5) I'll probably be using my small Wacom Intuos Draw or my mouse.
A: Trick question, I normally don't! I prefer doodling until something comes together from a concept either given to me by the prompt or the DTIYS. I really enjoy playing around with the character concept itself for the drawing because otherwise it'll just be them in white space. I feel like my illustrations are a product of my environment and I just get bursts of inspirations for a few days at a time before I burn out lmao.