Number 1: try out Spitfire Labs Soft Piano, it’s free and is excessively good, I didn’t even have to EQ it or anything, it just sounds so good off the bat.
Number 2: my thought process behind the themes was my desire to do completely contrasting themes. One would be calm and welcoming, such as a Christmas theme, and a when I got that down, I decided to make the next one brutal and oppressive, and I was listening to a lot of Russian/slavic styled music from games and movies, so I went with something along the lines of Papers Please and Workers & Resources Soviet Republic.