After 6 months (12 for small business) a casual can ask. You have 21 days to answer in writing, and only certain reasons count.

Wages, annual leave with loading, long service leave if it applies, plus notice or redundancy where owed. Not sick leave.

No. The minimum employment period only affects unfair dismissal. Other protections apply from day one.

One to four weeks depending on service, plus an extra week for some over-45s. Here is the table and the exceptions.

Probation is a contract term, not a law. For casuals, what actually protects you is the minimum employment period.