Hi Expat Nick
On the first rental you will need to pay 50% of the first rent to the agent.
Then the agents charge 15% monthly from the whole rent.
They will collect and deposit your rent on a montly basis.
If the tents are late 3 days paying your rent you are intitled to juros(a few extra pennies) being added onto that particular mth.
They willl deduct money for any repairs needed and will need to show proof of payments made to the registered companies.
You will have to make a declaration of earnings ,with receipts and bank statements as proof of evidence anually to the Receita Federal as the person you will be renting to on a longterm basis will be doing the same.
I would like to add that this is different from a pool system.
Extra-I use a very good small agency(for private rents)and they are very reliable.I prefer them to the big agencies as I get more personal care .They deal in the local market,but not in the tourist market ,so if you are planning on renting to Brasilians on longterm contracts they could be ideal.There actually is shortage of properties to rent out to Brasilians so you are on the right track.
Hava a nice day