Filled it out, some questions left me very unsure as what to say, like the 2D/3D question? It depends on the game, some games are better for 2D but i guess most are better with more than only left/right movements with a possible jumping.
I also found it curious with an app that followed in the game? It depends a lot on what the app does and if it affects gameplay, and how.
There were some things I felt was missing in what I might enjoy from a game, and it is a very simple to do but not out of the way, grind. There is the bad kind of grind where you play 20+ hours just grinding, and then there is the one where you just need to get better or preferably for me, grind my way into having an easier time playing. This doesn't mean I don't want a challenge, but I am unable to enjoy some games due to how they can sometimes feel like "git gud" games, and it just makes me try less and be annoyed more rather than try to get better. Some examples for me would be the Borderlands 2 game where achievements give you small (almost too small in the end) bonuses to a stat, or Terraria where sometimes it's all about finding better equipment to handle a situation. I guess some people would say Dark Souls since you just need "the right" things to take down a new boss.
As for Pre-ordering, I have done a lot of pre-ordering in the past on games that I really felt sounded awesome, but now I am so wishing I hadn't done so because it turned out to be games for a totally different sort of player, often people who think outside the box and like the gameplay to be brutal and punishing. Right now I don't have a lot of money to spend on games on a monthly basis, but around 10-20 Euro/Dollars does go to giving it a shot on sites like Chrono.gg, so if I were to pre-order, it would have to come with a Demo or similar I can try out first. Maybe a t-shirt too, but it's usually a very high cost for everyone.
As for where I prefer to buy my games, I do use Steam the most because it is often the one with most deals, most updates, but really I enjoy GoG a lot more as they are DRM free and it allows for playing games if the internet decides to die on me. But GoG doesn't always get updates etc, so it's an evil circle of no new content = no new purchases.
When it comes to the last question of "Non gameplay related content" and how much I would spend on it per year I am not sure what counts and what doesn't, if you mean skins and such I rarely, if ever, pay for such things.
Always fun being able to help someone out. Good luck Project 0814