There are hand techniques but they are fairly simple and generally not stressed in the context of the Roda. The Roda is kind of a game, even tho it can get aggressive and rough. The game involves a physical dialoge that creates a never-ending flow of movement. Throwing hand strikes often breaks up the rythm of the game so in a friendly roda they aren't used much.
Hand techniques would be used more in a fight with capoeira, which is different from the Roda. In a fight, it is a fight, and anything goes.
The techniques are fairly simple open-handed and fist strikes, while the hands may also be used to assist in making throws or sweeps. They don't tend to be developed into the complex techniques that many of the Asian arts use. Capoeira avoids blocking, as this also disrupts the physical dialog and the flow of the game. Instead, we dodge and avoid attacks. However, the hands are used defensively if it becomes impossible to avoid the strike. We use defensive postures with the hands to protect the head, and these can turn into something like a block. It is better to avoid the attack and not disrupt the flow of the game, but it is better to block a strike then get hit if you can't avoid it.
I have seen "friendly" rodas get nasty, and people start pounding on each other. Sometimes they end up on the ground grappling, and it turns into jujitsu. Once that happens, they are no longer doing capoeira.