How does the SPI protocol distinguish between the read and write cycles?

$2.$ How does the I$2$C protocol distinguish between the read and write cycles?

$3.$ You have one LCD and DS$1307$ RTC and you want to connect them to

Arduino kit to show the time. Both are connected to I$2$C bus, where the

LCD address is $0$x$27$ and DS$1307$ RTC address is $0$x$10.$ Write the C code

for displaying time on the LCD.