The downside of NewSoftSerial is that it is interrupt driven on receive only. I'll check out SoftwareSerial.
NewSoftSerial is the replacement for SoftwareSerial (hence "New" in the name). It is far superior to the old SS.
I need to use real RS232, and I found a kit with a MAX232 compatible chip. Is there a similar chip that includes some hardware buffering, ideally that is pin for pin compatible with the MAX232?
No. The MAX232 is a level converting transceiver; that's a very different task than a UART.
There are hardware UART peripherals, but I haven't seen any Arduino code for them.