Clocked Serial - SPI

The rabbit processors clock serial data out LSB first. This is the opposite from most SPI peripherals that clock MSB first.
What does everyone do - a lookup table?

That is correct on the Rabbit 2000 and 3000 processors, but the Rabbit 4000 processor can transmit or receive bits in either direction. The SPI library already has the needed bit reversal built in. In fact, it is the default within the library. You define SPI_NOREV to shut off the automatic bit reversal.

How fast is the SPI on a 4000 based microprocessor?

How many bytes per second?
What is a reasonable amount assuming that you are doing other stuff,
like transmitting over the ethernet connection, the data read from the SPI.