How can I gain an in-depth understanding of contact and contactless EMV technologies?

Answer:

The best starting point for your introduction to EMV Contact and Contactless technologies is at EMVCo.com  (www.emvco.com)

EMVCo is a pseudo-standards group created (and controlled) by the major card payment brands (e.g. VISA, MC, Amex, Discover, JCB, CUP).

EMVCo authors, manages and enforces the specifications related to the implementation and certification of EMV Contact and Contactless technologies for payment systems.

These specifications are used by terminal manufacturers (such as IDTECH) to develop contact and contactless interfaces on our products.
In addition, these specifications are referenced by the test labs that certify the proper performance of the terminals.

For Contact EMV technology, the core specifications are the version 4.3 “Book 1, Book 2, Book 3, and Book 4” specifications.
These can be downloaded from the EMV site at: https://www.emvco.com/emv-technologies/contact/

For Contactless EMV technology, the core specifications are version 2.6 “Book A, Book B, Book C (Kernel 1 – 7), Book D” specifications.

These can be downloaded from the EMV site at: https://www.emvco.com/emv-technologies/contactless/

If you browse the EMVCo documentation library, there are many other documents related to this subject, and which may be of interest at a future point.
However, for now, I would suggest that you focus on the documents referenced above.

Please note that it is NOT necessary to become an expert, nor to memorize these specifications.
However, a cursory review of these specifications will provide you with core insight into the electrical and logical elements that comprise these technologies.

They certainly provide a foundational base for further understanding and learning.
Would suggest that you download these specifications and keep them handy for future reference.