What topics can I ask about here?
Find out the distribution they run (for example, Ubuntu) and focus on that first. Use VirtualBox or another VM to play around, especially networking and the daemons that your host is using.
Other pages seem busted too. On https://networkengineering.stackexchange.com/help/closed-questions, I see:
What does it mean if a question is "closed" or "on hold"?
It depends on the framework you're using. Just use what it supports. Most web frameworks I've seen use the front controller pattern and call it MVC or MVP.