How much should a supervisor expect from students who have graduated? I have recently completed my PhD and taken up a faculty position at another institution. My new job is busy and I regularly get emails from my PhD supervisor asking me to write protocols or for information which would take only a small amount of effort for her to find (e.g. where things are in the lab; where to order things from; which product was used for a specific experiment). I left my lab books; wrote up detailed methods in my thesis and papers and showed a lot of this stuff to her new employee before leaving. She is quite aggressive about getting this information back quickly,but is slow (weeks-months) responding to my sending her revisions on submitted papers from my thesis.

What is the etiquette after leaving a lab? For example, would it be unreasonable to remind her where the methods are written up, rather than writing out protocols with all the dilutions etc worked out? I am not looking to continue to work with my PhD lab but I would prefer to maintain a cordial relationship.
She might be panicking. Normally, it's good practice (though not strictly required) to hand-over such lab information in a well-documented process. It is a good idea to make a hand-over closing date (even with friendly people) to make clear that/when the process is finished (of course, you could help for isolated questions, but this should be the conclusion of the main process).

My suggestion is: create an overview of what you need to document and with which your task can be considered essentially complete. She cannot expect you to document everything - unfortunately, that transition would have had to happen earlier, with a newer research student. When a research student leaves, it is normal that know-how leaves with them, sadly. 

The fact that you write papers together lets this boundary blur, so you may have to pay a higher "tribute" cost to her if you want to maintain relations. However, I think, with friendly pointers to the precise locations where it's written and trying to promoting a habit of actually looking it up there, you may get somewhere. Some people have a hard time to follow rules of search for other people's work, and your task is to try to break that habit gently.