what do i need to know about nachos system.

from now on, i need to study with nachos system, a micro-operating system.i need it to implete it very soon.for clear the goals, i'm listing serveral questions which i need to work out as below, i'll answer them as i study about the system:
1.how do all the pieces of an operating system fit together?
2.how does the operating system start a thread?how does it start a process?
3.what happens when one thread context switches to another thread?
4.how do interrupts interact with the implementation of critical section?
5.what happens on a system call?what happens on a page fault?
6.how dows address translation work?
7.which data structures in a file system are on disk,and which are in memory?
8.what data need to be written to disk when a user creates a file?
9.how does the operating system interface with I/O devices?
10.what does it mean to build one layer of a network protocol on another?
total ten questions, for understanding these question, i need to read the source code.it's a huge project,i think, but i'll finish it in days or weeks(if i got enough time).

the answers(in updating):
1.the system is divided into three parts:one is hardware simulation,above it is portable OS kernel, the last facing to the users is user programs.each part has its own content,listed blow:
hardware simulation including I/O device simulation and machine-dependent OS layer.
portable OS kernel including thread management, file system, address spaces, RPC(remote procedure call) and TCP(transfer control protocol), virtual memory and syscalls.
user programs including MIPS(million instructions per second) simulation and shell.
they just like building blocks, one by one, step by step.
hardware simulation is at the bottom, the portable OS kernel is at the middle, and the user programs is at the top.
above is introducing how does the nachos system fit all the pieces.