Where to find official publication ethics guidelines and best practices?
I would suggest to follow the COPE (Committee on Publication Ethics) guidelines to get enough idea on your mentioned issues. You could also find the some exemplary cases (here) and how are then being handled by journals or the COPE boards.
Briefly, it says:
&quot;COPE is a forum for editors and publishers of peer reviewed journals to discuss all aspects of publication ethics. It also advises editors on how to handle cases of research and publication misconduct.&quot; (Source: COPE Homepage)
Further, you could also find publisher-wise publication ethics guidelines, though they follow more or less the same practice:

Elsevier Publishing Ethics Resource
Springer Publication Ethics for Journals
IEEE Publication Ethics
Wiley Publication Ethics Guidelines for Authors
ACS Code of Ethics

A brief browsing through the above would give you a lot of information on such stuff, which one must know before entering into the research world.