There is no visa on arrival. There is no transit visa. If you need a visa (depending on which passport you hold, which you have not specified), you should leave enough time to get it from your 'home' Brazilian Consulate.
Yellow fever vaccination has two reason. To protect yourself in an area that has an outbreak, which is not GRU afaik. To gain entry into a country when coming from one that has an outbreak. If you are going to Quatar, ask those officials if they consider Brazil, even just the airport, to be of sufficient risk for them to require a vaccination of you.