RE: Can we trust peer-reviewed papers?
Journals have been a great gatekeeper for science for hundreds of years.
While you can blab on and on about impact factors and the overall quality of the journal, I have always treated each article independently. While some journals have rigorous standards, there can always be exceptions.
Citations are a really important part of the equation to keep in mind. There is no substitute for following up on an article and doing your research.
Maybe most importantly: Open Access
Science, unless happening behind closed laboratory doors, should always be open and shared. From pre-prints to final publications, access should not be restricted. If you plan on publishing, your audience is the world. Not the patrons of some corrupt journal.
This is why I support projects like http://sci-hub.bz
Enter a DOI and boom you have a PDF. No login required.
I am lucky that I have access to a university library, this is supposed to be free for all.
Thanks Kyle. Great comment. I agree, information wants to be free and to spread! :)