Focusing on the question, of how much research you are expected to have done before asking here, and answering only for myself.
I wrote an answer for a similar questions about Stack Overflow some time ago. The gist of it is that asking the site things that you could have easily (or perhaps trivially) googled comes down to wasting the time of people looking at your question, and those questions shouldn't be asked. The final expression of that idea there was:
It is the same as not asking when the answer is in the furnished manual or the first half-dozen links that Google brings up. The answer being in some obscure usenet archive or 400 comments down in a slashdot thread on some other topic is no impediment to asking Stack Exchange, but there being dozens of answer instances all across the internet is.
I figure the situation on Physics is similar, but not necessarily exactly the same, because it is (in my opinion) easier to to see but not understand a treatment in physics even when you have the minimum preparation for the topic.
Asking before you have looked at those resources that Google brings up right at the top is a waste of other people's time.
If you have looked and still don't get it, tell us what you found unsatisfactory about those treatments. And "I didn't understand" doesn't count; say where your understanding broke down. I you stuck on a step in the math or on how it could be written in terms of that math in the first place?
Be clear about your level of preparation. I've seen so many questions where the OP claims to understand field theory and relativity, but has actually just read some pop-sci book that I can usually guess what the case it, but you aren't doing anyone any favors by muddying the water that way.
Asking for a detailed description of a topic at your level when you simply aren't prepared to deal with the math is a waste of other people's time. We have been open to "layman's terms" questions, but you have to accept that those answer will be in layman's terms.
All that said, part of the goal here is to build a comprehensive database of good questions with good answer. So, shouldn't we allow ever good question, even if they have been answered well elsewhere?
Well, we should, but it is fair to insist that we work on really good versions of those questions, and that really calls for someone who knows the topic to craft the canonical version of the question.
Any way, those are my thoughts I've wanted for some time to sit and hammer on them to find where they might not be internally consistent, but I never seem to find the time. So perhaps some of the rest of you can show me those spots.