I am a lazy developer so here My Recommendations for You :)

If you code, your body and mind loose a huge amount of energy. Which you will not gain in a few second like your computer do. Think that you are a Human not a Super-Human. So eat and do sport before doing Software Development. Checkout in here http://health.phleton.com/

1. For simple questions in HTML, CSS, and JavaScript checkout w3schools.com before asking questions in here and build a SAPUI5 application to be able to save your most relevant information and website link to categories so it will be easier for you to click to find the relevant informations that your require. For the future, see in here http://apps.phleton.com/
2. If you develop a Software Keep-It-Simple. Understand the Problem : Code Less, with Maximum of Usability. Encapsulate everything in methods and helper classes. Use an advanced IDE for building Softwares.
3. Develop a Software only once, then copy it and customize it to develop other Softwares. If you think your software is good, then try to change the technology (e.g. of the UI) and you will quickly understand that your software is not good as you think. That is why Microservices are the future.
4. Last but not least, code a Clean-Code and document it. If the complexity increase, you will loose your mind trying to figure out the errors. So always do a clear code without going to deep in complexity. Log everything, so that it will be easier for you to find the errors and bugs to quickly fix them. Logging will save you a huge amount of energy. Smart coding is the answer!
5. Yes, do a Unit test to check if your software is good as your coding.
6. The new software answer of the future, is called Microservices Architecture. Well it is a good design to use, because your software is a bunch of services, that can be changed, so yes your software will be agile. Forget your Monolithic Architecture. You are no more depended on certain technology stack. You can use one service in Javascript, the other in Java or whatever. That is called the "Democracy of Software Development".
7. Last think I say to the industry. If you consider me to be dumb, because I have a lack of understanding, than I tell you, you have 0 idea how you will tackle digitalization and migration of legacy systems in the age of digital disruption. So, I'm currently the smartest jobless Software Developer on the planet O:) see me how I refactor weired code on github.com/phleton/ and join me on researchgate.com to see what the smartest people do for the future of software development and forget what the industry is telling you and is doing. I suggest you to -> Go make some agile development movement on the fitness studio to live longer than your software: "Live long and prosper". License under the EARTH LICENSE 1.0 (http://www.phleton.com/license/earth-license-v1.0.html)