Newbie - Help & Clarifications

I'm new to CNC

I understand that the tool has to be homed to get a physical
reference to the m/c in relation to which the tool will be moved.

Is this done with a switch to which the tool has to be moved, and
the when the switch closes, the tool is stopped & the position
becomes the home position ?

If the above is true , then what is the accuracy / repeat accuracy
possible with home switches ? Are there any special switches
available for this purpose ?

Is there any other method for homing ?

Are there any sites / books where I can get my basics of CNC -- like
the question above ?

Any help from all you so knowledgable people is welcome ?

Biswanath