Most of the problems you've listed become easy the more familiar you are with data structures. This is a more common problem for anyone outside the SV/SF bubble and I wouldn't worry. Just start doing homework and you'll be fine.
Once you're done with data structures, I would start checking out design patterns: http://shop.oreilly.com/product/9780596007126.do
Hope it helps
You have the ability to write some code! If you want to get a jumpstart, you should take the princeton algorithms course (for free!): https://www.coursera.org/learn/algorithms-part1
Or read the textbook by sedgewick that accompanies the course. https://algs4.cs.princeton.edu/home/
There is very little math in there - it may take some elbow grease and mentorship to help to convey some of the ideas - but I believe that you could implement and solve most everything in there. That was my path - I had a teacher at the age of 14 who would explain to me how different algorithms worked and I would go and implement them. Drawing a circle (in memory - it was in C!) or sorting a list (we did bubblesort first IIRC!)
I think you could do it! I believe in you! The course material is approachable - much more so than basically every other algorithms/data-structures material I've found. it may take you some time but you'll be soooo far ahead with your thinking about code.
If you ever start working with Object oriented languages like Java, another book that may help you when you've gone down the road a bit is the Head First Design Patterns book. http://shop.oreilly.com/product/9780596007126.do It's very easy to read, mostly pictures. It is made to be very easy to read (all of the books in that series are so look around at them.)
It's helpful to do both - code and also take in some material, but at 12 I imagine some of the material may be a bit daunting. You're doing really well - keep it up.
Abstration can take many forms. But can often be described as "seperating things that change and/or repeat from those that don't", or something like that.
The last paragraph may be a joke, or based on one of the Principles in the O'Reilly Design Patterns [2] book.
[1] https://mitpress.mit.edu/sicp/ [2] http://shop.oreilly.com/product/mobile/9780596007126.do
I would recommend picking up a free chapter of the old one to see if you like the style of presentation.
Personally I just love the way they present information.