Can you please help with these Linux question about directory

Questions:

1 - Answer the following questions about the directory size:

a) What is the size (in MB) of the /etc directory?

b) Which directory is bigger: /etc, /bin or /sbin)?

2 - What is the purpose of the watch command?

3 - Answer the following questions about memory:

a) What is the total amount of memory (RAM) installed in the Course Server?

b) What is the amount of used memory?

c) What is the amount of free memory?

d) What is the amount of shared memory?

e) What is the amount of available memory?

4 - What does the symbol > do in the command dir > myFile?

5 - What does the symbol >> do in the command dir >> myFile?

6 - What does the symbol | do in the command dir | find myFile?

Thanks