Not wrong as much as plain impossible. Most masters of the field tend to be experts in only a couple of domains and/or sections of the infrastructure/process, and only in a handful of languages and frameworks at that.

I love solving bugs. The more challenging they are, the more I immerse myself in the technologies used and the more opportunities to refactor I see. Maybe I just haven't found an annoying enough bug to put me off but, yes, I think debugging is pretty interesting.

The title of the question seems unrelated to the body. In any case, the quality of the software is orthogonal to the price or availability of the code. Comparing prices, the advantage of free software is that it's free; paid SW has no inherent advantage. Comparing openness, the advantage of OSS is that I get to look at the code and improve it if I want to, closed software has no inherent advantage. I work as a developer so I don't have many chances to use closed SW in my line of work anyway, pretty much open libraries/frameworks or the code I write myself.

If with "design" you mean "user interface", then not, you don't need one for the other. They're completely orthogonal skills.

Tuples are immutable. Once you declare it, you cannot change it, which is why they don't have methods like append. You probably want a list, that is declared with braces [] .

As much as I don't like either of them, I think Java and C# win in the IDE department. JetBrains's IDEs are great, but Eclipse and Visual Studio have more features and are more widely used.

I like both Python and JavaScript and I think both are very good languages that will get the job of web development done. I have a slight preference for python (used to be wider before es2015), though, and I think it encourages maintainability and readability a little better than js. That's about as much as I can say regarding backend work. Now, for other pastures, Python has better prospects in the market. One would be hard-pressed to find JS in something other than web applications, while Python can be used for machine learning, data science, embedded systems, desktop development, etc. But you already know JavaScript and, if you feel like web development is enough, there's really not compelling reason for stopping its use.

My opinion: I like Python far more than PHP, right down to the syntax. I use Python. Python has better prospects in the market. One would be hard-pressed to find PHP in something other than web applications (where Python has become about as popular anyway), while Python can be used for machine learning, data science, embedded systems, desktop development, etc.

If the employee is not stealing your intellectual property and is performing well and on time, I see no reason. When I was en employee, I'd have probably quit on the spot had I been micromanaged like that.

As a manager, I would think "I just spent 10k to educate this person and to fix a problem in our development process. That's an investment I won't risk ruining by acting irrationally."