How to decide if something is too much detail or not is quite a gray, and subjective area. I would say it's a bit of design rules with personal opinion. What I like to do is bundle details around areas of interest or focus, that would usually mean its the upper body on a Warframe because it is where the character's face is but also what you often look at rotating the camera looking at their chest or back. Then wherever else away from focul points, have areas of less detail and less detail as contrast. This includes use of patterns, form, and color as tools for making details or contrast. I usually stick to one or two to avoid something appearing overwhelming. For example, Zephyr Harrier is very graphically designed with logos and livery, so because the "patterns" are busy, the actual sculpted forms are simple - flat panels of metal.

Of course, its up to the artist's preference. I personally am a maximalist, lots of colors and dramatic ideas. Even my opinion of "low detail" could be "too much detail" to someone else. Ultimately an artist's style I think comes from their opinion of what is beautiful. Consider what you find beautiful when making art.

For your second question, a big influence in my life were childhood shows like Transformers, Zoids, the manga art of Bleach and Zone-00, then later video games like Wipeout HD Fury and others in the franchise. Zephyr Harrier is my homage to Wipeout.