No problem. You can read as much as you like, you can also download the source files no problem. We are just worried about people who counterfeit materials like text and images and post them in other websites without approval.
For multiple byte transfer, you just have to keep the chip select bit low for a particular slave between every byte by setting the CS_SetLow(). After the last byte, you can deselect the slave by setting CS_SetHigh(). You can use a loop 6 times or write the exchange function 6 times.
Since SPI is a synchronous protocol there should be no issue with having a delay in between bytes provided the select is maintained.