1.) A person who is on probationary status may, if they like, question whatever they want. With a couple of exceptions*, they may also be fired if they question the wrong thing or the wrong person. The same is true of employees who are not on probationary status. This does not mean that they WILL be fired; only that they CAN. Whether they will or not is entirely up to the employer.
2.) Absolutely not. An employer is SUPPOSED to have the same expectations of a disabled employee as a non-disabled employee**, and multiple courts have ruled that an employer cannot be held liable for not accomodating a disability that they do not know exists. This also is true regardless of whether the employee is on probation or not.
In other words, at least as far as your two questions go, probationary status is immaterial.
* Any employee, regardless of probationary status, can report illegal discrimination or sexual harassment without fear of reprisal. Any employee, regardless of probationary status, can file a report of ILLEGAL (not unethical, not immoral) activity without fear of reprisal. In some, but by no means all, states, any employee, regardless of probationary status, can complain of illegal activity internally without fear of reprisal. However, beyond that, any employee, regardless of probationary status, should be aware that they have no legal protections should the employer decide to terminate them. Again, that is not to say that any employee who questions anything is automatically out the door. Many employers have no problem with employees asking questions or making suggestions. But barring the exceptions above, there is no legal protection if the employer chooses to take offense.
** The ADA, which I assume is what you have in mind (if not please explain) does not require an employer to accept substandard work or lower expectations of a disabled employee - only to provide whatever accomodation may be reasonable in order to assist the employee in performing the essential functions of their position, and they only have to do THAT if the employee self-identifies him/herself as being disabled and requests the accomodation. The employer does NOT have to guess.
