I did the simulations with the TL70 series, in the final PCBs I used the LMs because I have more lying there.They are excellent opamps and it does not matter for the print layout.I think you can use many types if their GB product is high enough.I chose DIP8 / 14 because that is easier for DIY, therefore the PCB is also single-sided.the TL72 / -74 are still available in DIP as is the LM833 but the 837 is apparently no longer available in DIP.You may be able to use an adapter, but I would try the TL074 first.  

Nice project, do you have any more information of the  linear encoder used Regards Alfred

Dear Steve, thank you for the clarification.

I noticed the difference between the schematics and the PCB too. They don't match.

The USB connector is on the ESP32.  That is where the firmware resides.