There is a good post by “assaji” over on dhamma wheel:
https://www.dhammawheel.com/viewtopic.php?t=12694
Dr. Bimala Churn Law wrote a good article (in the 30s) that updated the one linked to earlier by Rhys Davids that can be read here:
Around the middle of the century G C Pande wrote a good book on the subject called Studies in the Origins of Buddhism which can be downloaded here:
The Oxford Centre for Buddhist studies offers a 2 year masters course that may be of interest:
They also have a journal the older articles from which are freely available:
Our own @Khemarato.bhikkhu has the excellent Open Buddhist University at:
@sujato of course runs the amazing:
There is also the equally amazing digital pali reader:
As for your question on chronology and stratification you may be interested in the thread:
Oh! And of course @cdpatton has the fantastic:
https://canon.dharmapearls.net/
One thing i would caution you about is that this topic can be a contentious one, and despite its focus on the early Buddhist texts this forum tends to accept that they are all from a relatively homogeneous period and more or less all go back to the buddha, so if this is of particular interest to you you may want to engage with other forums to balance perspectives.
It would be wonderful if we can get more people to contribute to this thread, there has been rather a lot of threads recently that don’t really directly relate to the EBT’s except in the loosest way of being discussion about Buddhism from a “non-Mahayanan” perspective.
Good luck!!