The Design of Everyday Things by Donald Norman
It's not about specific software related usability however it will give you a language in which to discuss usability and the types of mistakes people do and how to look as interface design from a user perspective.
You could use a bar, filled up as complexity increases. I wouldn't go with the green, yellow red approach because of the monochromatic design you already have, so maybe something in shades of blue filling a bar. Something like what is done in this article: https://medium.com/design-ux/9fe7b6715a1f
I've personally never worked with someone with an HCI background but I do know a few at different companies. I'll mirror /u/Playerresearch in that the GURSIG is a great resource -- if you're interested in meeting people who most definitely have that background working in games try to make it to the GUR Summit this year (it'll be at EA Redwood Shores (just south of San Francisco)).
Here are some books I'd recommend:
The Design of Everyday Things Don Norman Great starting point - the "why" of design, and why it's vital
The Humane Interface Jef Raskin A great perspective on human-centered technology design, from the dude who basically designed the original Macintosh
Sketching User Experiences: Getting the Design Right and the Right Design Bill Buxton This one's great for practical skills in a product cycle
A Project Guide to UX Design Russ Unger & Carolyn Chandler UX's role in a whole product cycle
The Visual Display of Quantitative Information Edward Tufte Ok this one's just fun. Tufte is an expert in Information Design, and an artist as well. He is great at explaining what makes images understandable and how to codify information.
Don’t Make Me Think Steve Krug This is a web-design standard book. Great for thinking about first time user experiences.
Dan Ariely talks a bit about how a mental "hot state" changes user behavior. Needless to day, users of a porn site are likely in a different state of mind than those browsing amazon, etc.
Read some more here <https://en.wikipedia.org/wiki/Hot_cognition>
The book I reference is called "Predictably Irrational". To summarize one of the results, users are more likely to be forgiving, and more likely to be persuaded when in a hot state.
Not exactly/completely relevant, but the W3C Web Content Accessibility Guidelines (WCAG) are a good place to start for websites.
Also ask yourself the following questions. These are based on those Donald Norman included in his discussion of the seven stages of action - I have reworded them to be more relevant to screen-based UI design.
How easily can users:
I'll restate that these are much modified from his so they make more sense out of context. I recommend you read his book The Design of Everyday Things for better understanding.
Ask your boss for a month of browserstack (https://www.browserstack.com). It is cheap and good enough.
Don't bother with the "emulators" like the responsive design mode of Chrome. It is a terrible way to develop for mobile devices, there are horror stories about that tool every day.
I can't claim this is the bullseye answer for your question because you have to sift through a little, but still... I cannot recommend this book enough:
Great book for anyone who is looking to get into UX work. Over views a lot of studies and how to apply research on human behavior (cognitive bias). Very interesting and a lot of great take aways.
Thinking, Fast and Slow: http://www.amazon.com/Thinking-Fast-Slow-Daniel-Kahneman/dp/0374533555
I can't claim this is the bullseye answer for your question because you have to sift through a little, but still... I cannot recommend this book enough:
It's really hard to recommend something with just one image. The chrome is pushing the relevant part (content) far down the window. There is definitely too much going on the top part of presented screen.
Personally I like how reddit is fun app is dealing with sorting. Maybe this reference will help you.