What circuit should I study, to learn all the details of the 555 timer?
To get a better overview of all the features of an IC, you're usually going to want to read the product datasheet, rather than expecting any example circuit to demonstrate all of its capabilities.

If/when the datasheet gets a bit too deep for you, it may help (when using as popular a component as the 555) to read The Wikipedia Article for an easier-to-understand overview.

Finally, if you still want/need some (more) example circuits to follow, or want more information/calculators/etc for using the chip, you could always read the Entire Website Dedicated to 555 Timers.