CRC32 / RS485 / Endianness

(Sorry for my limited English ability and technical ability.)

I have some questions about CRC32. Please kindly guide me.

(www.gelato.unsw.edu.au/.../crc32.c)

To check the CRC, you can either check that the
CRC matches the recomputed value, *or* you can check that the
remainder computed on the message+CRC is 0. This latter approach
is used by a lot of hardware implementations, and is why so many
protocols put the end-of-frame flag after the CRC.

Note that a CRC is computed over a string of *bits*, so you have
to decide on the endianness of the bits within each byte. To get
the best error-detecting properties, this should correspond to the
order they're actually sent. For example, standard RS-232 serial is
little-endian; the most significant bit (sometimes used for parity)
is sent last. And when appending a CRC word to a message, you should
do it in the right order, matching the endianness.

1. One another article says that, check if ( CRC(buf + CRC(buf)) == 0 )
is the best/fastest way to do the CRC verification. But I am wondering
if this is good for software? I don't see any performance enhancement,
because I still need to re-calculate the CRC value for the whole packet/string.

2. The most popular polynomial for CRC32 is 0x4C11DB7, which is designed
for IEEE 802.3 Ethernet; So I think it is designed for Big Endian.
However, I want to use this on a RS485 Net, and the UART Transmission
is based on Little Endian, If someone wants to get the best error-detecting
properties, should he/she needs to reverse every Byte? And if needs, is this
the only thing he/she has to do?