Build everything, the best world: CREATE, if you need money that fast, i would recommend udacity. Its not very cheap, but for what you get back, it is worth. If you need some specific thing to complete your learning, go to udemy. Coursera is also good. But remeber: CREATE anything that is cool and useful in some eay.

Python for data modeling and c++ for activities that need more speed

Dividing them in functions, or even in different files

I dont have experience on freelancing, but i know that there are many websites like upwork and freelancer.com that you may find someone that fits your needs.

Go python, its better for it

Programmers = all themes dark