you should follow this schematic design if you want to get this module working.

Also If I want to change the UART pins to other pins would it work without errors or If I want to use 2 or more UARTS? same with I2C

Also what are the debugging options available sins the RS232 is not connected to the MCU like in an arduino how would I set stop points or peek at variables values to see if the code runs as expected?

Check on adafruits feather reference they use two resistors as a voltage divider for that simple and effective.