The ‘Add New’ button should open a new window to create a leave policy. If it doesn’t work, then maybe any other plugin conflicting with that button and made it disabled- I guess.
You can do it in two ways. While creating the leave policy and from the leave entitlement. No, you can’t have a policy individually for the employee. If you have different leave days for different employees, then you need to consider creating multiple policies.
Umm, you can entitle the leave policy based on departments, designations, marital status a few other variations. Also, you can entitle the policy for the selective employees as well- where you need to search with the employee name to select them.