Learn English – the proper way to ask two questions in one sentence

My impression is that the phrase was written by a non-native speaker of English, who does not know how to construct questions. (How often that impression is accurate I don’t know.) All of the examples you offer are noun phrases. For example, “why we need SELinux” might serve on its own (sans question mark) as a headline, or as part of a complete sentence:

• Tell me why we need SELinux.
• Why we need SELinux is…

But the terms may not stand on their own. English questions use inversion of word order and auxiliary verbs; noun phrases involving question words do not:

1. *Why Paul went to the concert?
2. Why did Paul go to the concert?
3. Paul went to the concert.

The people writing these question titles are using (1) when they should be using (2), because it more closely mirrors the structure in the declarative version, (3).

Now, “Why turn ‘collate’ off?” is incidentally valid. It poses a rhetorical question using the bare form of the verb (in this case turn), asking essentially “why would you ever bother turning the ‘collate’ function off?”—why here is standing for why ever. Common examples:

• Why bother?
• Why wait?
• Why waste your time?
• Why not?

The suggestion by Gary's Student to use bullet points is a good one.

If the questions must appear inline for some reason, you can number them instead:

Before we can examine the implications of neuroscience for criminal law, we must address two more fundamental questions: 1) Why do we punish criminals at all? and 2) How severely should we punish them?

With a longer inline list (perhaps three or more questions), use semicolons to separate the items. For instance:

Before we can examine the implications of neuroscience for criminal law, we must address four more fundamental questions: 1) Why do we punish criminals at all?; 2) How severely should we punish them?; 3) To what extent must punishment emphasize rehabilitation?; and 4) Should the family circumstances of criminals be considered when sentencing?

The semicolons aren't necessary for clarification, but they encourage the reader to consider each point more thoroughly by slowing down their reading of the list.