Project transition from Teensy 3.6 to 4.1

[NewtoTeensy]

Hello,
I am new to developing applications on the Teensy. i am inheriting a product that has been developed on the Teensy 3.6. i now need to move to a Teensy 4.1. My application use PWM, CAN and DACs. The Teensy 3.6 sits on a mother board with the external interfaces. I use the Arduino IDE for the software development. I understand the 4.1 is an upgrade to the 3.6 and that it employs a newer processor. My questions are:
1) HW: many pins seem to be moved. Also, the pins are configured differently. I am sure I need to do a re-layout of my board. Do I need to re-design my hardware board completely? Or do I just need to make some layout changes to accommodate specific pins?
2) FW: Are libraries available for the PEM, CAN, DAC drivers on the 4.1 (which will be a drop-in replacement for the corresponding 3.6 libraries)?
3) FW: Can my current 3.6 application be largely reused? What changes will I need to make?
Any guidance would be appreciated.
Thanks.

 

[BriComp]

Without seeing the project and software would be just a guess!

Instead of re-laying out your board what would be usefull would be a conversion board.
I suspect there would be many people in the market for such an adaptor board.

Plug Teensy 4.1 into adaptor board, plug the adaptor board into your T3.6 socket.

EDIT: Having just looked at boards side by side, a generic adaptor board probably is not feasable.
Might be good for your specific case.