The TV schedule is fantastic. It allows you to have a life. Theater actors are so disciplined - especially if you're doing musicals, you have to be in shape physically, mentally, and have to be on your game all the time. That's exhausting. On TV, especially a sitcom, you have a lot of free time to play.
The voiceover thing is very selfless. You go in there and they've hired you for your voice, but they know exactly what they want, and the writer's there and he knows exactly how it's supposed to be said. So you can't really argue with them, you just have to let them tell you what to do and then do it.