Most importantly it depends on what type of business as different rules apply depending on what type of business you want to open!Will you want to work alone,company simples partnership etc,etc ?

Accountants are salaried on a monthly basis.
All salaries need to be registered and all inss paid for staff otherwise you will probably end up in court!
The best thing to do is check with a lawyer who understands brasilian law.There is one in the lawyer thread with her email and she speaks english fluently as she lived in the States for a number of yrs and is now in Natal.Her name is Carol.