Does disability impact on prospects of employment in academia?
Self-identifying a disability at some stage during the interview process is usually in your best interest. Being upfront with a potential employer can make all the difference, especially because of the legal protections it affords you in most academic settings. It's also important because then expectations are properly set at the beginning of the process, rather than having to "adjust" later on.

Additionally, many application processes (at least in the EU) allow for self-identification of illnesses and handicaps that could "slow down" one's career. This allows one to "lengthen" the eligibility clocks for many programs. This helps to ameliorate the problems you mentioned of being judged against a cohort that has had more time to work.