There are both thin film circuits and pcb circuits. Pcb circuit is responsible for signal processing,

Thin film circuit should be called silver paste thin film circuit, which is only responsible for.

The transmission of status signals is high impedance. Because it can pass a small current.

Generally does not have functionality.

How to add some components, such as diodes or resistors, to thin film circuits?

It's not usually used this way. It is only used as a normally open key switch.

I want to learn film circuit, how to learn it, and what books can I get started with?

There is no special book, just a craft, and you don't need to learn it specially. You can draw this kind of circuit if you can draw PCB.