Yes, you can take a break anytime you want and start again at your convenience.
But keep an eye on your task deadline; if you think you need more time, please notify the responsible PM so they know you need an extension. You can do so by leaving a comment in the task’s specific thread, which you can find under each task on your “Claimed Tasks” page (at the top of your homepage, right beside “Home” tab).
To answer this :
Always make sure your device is connected to internet, each segment will be auto saved once you press “confirm” button. Also, if you decide to leave a segment half done and come back to it later, just move to the next one – it will be instantly auto saved if your internet connection is active.