This is something that could be examined fairly easy using a Google spreadsheet or another means for "crowd sourcing" to collect the data necessary to answer your questions. Specially, set up an online spreadsheet where authors could provide, for each of their published manuscripts, the following pieces of data:
1) date of initial submission in MM/DD/YYYY format
2) date of initial action letter in MM/DD/YYYY format
3) date of resubmissions in MM/DD/YYYY format
4) date of acceptance in MM/DD/YYYY format
Once these data are submitted, analyzing them using spss, R, or another software would be relative easy and would answer the questions you posed.
Authors could also include the number or revisions necessary before a paper was accepted for publication and could also provide their subjective/preferred number of days between an initial submission and an inital action and between initial submission and publication. Authors could also provide the names of the journals they submitted to, so you could examine differences in publication time and action time across sub-fields.
The reason I suggest this approach is that my university's curriculum committee, which I am part of, recently started examining the lag time between the submission of a curriculum review proposal and final approval of the proposal. We decided to divy up the work and we have been posting our data to a Google spreadsheet, which has made the overall task quite easy. If you are interested, I'd be happy to begin settling something like this up.
Best,
Bryan
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Bryan R. Burnham, PhD
Associate Professor of Psychology
University of Scranton
Scranton, PA 18510
Twitter: @DrShaggy