For the last question, both yes and no. They become weaker in terms of how much weight they can hold, but that’s usually not a problem. What often requires thicker timber is typically that it shouldn’t bend in the middle, so it doesn't matter if you notch a bit at the ends, for example.
You can place a roof rafter out far enough so that you can use it as a fixture for the panel, possibly adding a small rafter like a 45X70 outside the roof rafter to get some distance if needed.