Many items that matter greatly to me in determining whether a job offer is acceptable tend to only appear in employee handbooks after accepting a position -- and are presented as non-negotiable requirements for employees to sign.
Examples include specific terms about intellectual property policy as it relates to open source software development and projects undertaken when I am not on company time; any firm-wide policies about severance pay; policies about leaves of absence, vacation accrual and roll-over, and maternity/paternity leave.
All of these matter very much to me and they all have to be acceptable for me to take the position. However, asking specific questions about these items is usually not taken well by hiring managers. It gives an impression that a candidate is impossible to please, when in reality these are hugely important issues that affect my life as an employee. I'm often very surprised how little many other employees seem to care about the details of these issues given how much they impact the properties of the job.
Given that, is it fair to ask for a copy of the company handbook at some point later in the hiring process but before accepting the job? Is it fair to highlight certain policies and ask about whether exceptions have ever been made for other employees in the firm, and if so, whether exceptions can be made for me as well?
If not, how can an employee learn these important details ahead of time? It's very likely for me that the interview process, salary offer, and other features could make the job seem acceptable, but then a blanket policy of never paying a severance package, or claiming IP ownership over any and all software projects undertaken while employed, for example, would be instant deal-breakers.