A colleague of mine has notified me of an upcoming opening for a TT position in my field in the US. She told me to contact a colleague of hers in the department hiring to "ask for advice" regarding the position. Being from Europe, this a bit unusual and I am at loss about what I should ask for since the position already comes with a job description? Is this just a way to informally establish contact? What types of question are appropriate/inappropriate to ask the person in this situation?
I would keep it simple. Typically at this stage I have asked questions like “Are there sub fields that the department is particularly interested in hiring for?” “What courses are you hoping this position would cover?” Or the fallback/generic options “Is there anything beyond what is in the job description that I need to keep in mind when applying?” And “What aspects of my CV do you recommend I stress in my application?”
The goal is to use the conversation to introduce yourself and to tailor your application.
I assume your colleague knows something about the culture of the place she recommended. If so you should probably follow her advice. There are a lot of things you could ask other than "Would I get the job?". You could ask about things like local working groups (seminars) in your sub-field, for example or things about students if that is part of the position. You could even ask things about living in the city in which the place is located. Local ambiance, and such. It is likely a mistake, however to ask too many questions, but a conversation might develop.
In fact, if you hope to have a longer conversation, you might make the initial contact letter very short. "What should I know about your department?" or "Is there a lot of collaboration within the department?"
Some things you can learn with a bit of research, such as the names and research interests of the other members of the department. Others are harder to learn, but also important to know. One is the general collegiality of the place and how difficult it is to attain tenure. But some questions probably shouldn't be asked by a potential candidate until they express interest in you.
But you could also ask your colleague to write to this other person on your behalf with a simple introduction. She can also ask some of the questions that you can't really ask directly yourself.
Of course, if you write and get no answer back, you've learned at least a little something about the place.