Some people feel that battery is used more quickly with both on. I was just reading a similar question on another forum. To be honest, with cellular data, battery usage is dependent on signal strength. If there is a weaker signal, then the battery will show more use as the cellular radio will work harder. I don't see that much difference, and I have both cellular and Wi-Fi on all the time. When within range of a known Wi-Fi, my phone uses it. When not, then I'm on cellular data. I do not see that much difference in battery life, and I believe that going into settings and turning off and on cellular data will use more than just leaving it alone. At the end of the day, I still have battery left, and I charge my phone overnight for use the next day. Many days when not at work, my phone can last for 2 days without a charge. People can tend to read things and get overwhelmed by 1-2% battery for no real reason.
So, to just address your questions:
1. Yes, somewhat
2. Yes, but not to the point that you are going to watch the battery level decrease before your eyes.