We or "the authors"? Now, say authors A and B are writing their second paper. Which is more appropriate, or which sounds better. Referring to their previous work as "we researched/we surveyed" or "the authors researched/surveyed". This warrants a question because, in the first case, it may sound like they are "broadcasting" their presence, while in the second case, it seems like they are "hiding" their identity. 

Although, the following questions 1 (which applies for a single author case) and 2 (which refers to when there may be many authors but some of them may not share co-authorship in a new publication) are similar, they are quite different from what is intended here. Also question 3 is quite close, but I guess the question applies for use in a thesis.
I don't think it makes much of a difference; both are used widely. Some people like to write their names as well, eg. J. Doe may write, 'Doe et al [22] demonstrated...'.

The last one is important if you're submitting to a double-blind review. Between the first two, it  depends on how much attention you want to draw to the previous work- it could be of prime significance, or it may be an offhand, supporting reference. In the first case, you may like to use 'we' to establish your group as an important contributor in the field. Nothing hard and fast, it's quite subjective and a matter of style- most people would consider 'the authors demonstrated' to be a more formal expression.