It is different for each employer and is offered to employees when and if an employer decides to include it in their benefits package. Some employers don't even offer it. You are fortunate to have it. All qualified employees should receive the same amount. Check your employee manual. The extent and limits it will be clearly defined.
Employed or not.... Most short term disability coverage will max out between 8-26 weeks. Then long term disability kicks in. If you had the claim while employed you should remain covered even during lay off.