Bring a doctors note if you are sick more than 1 day in a row or you will be written up. (cost WONT be covered. Around 30$ at walk in). However sometimes they ask you to bring one in and then never check for it making it a waste of time.
You just call in when you're sick for part-timers. There wasnt really a limit. If you're sick you're sick. Unfortunately some managers will chastise you and gossip about you when you take that day off.
5 or 6 depends on the crowd!