There is nothing wrong with your analysis of #1. After adding, you (correctly) got x=5. All that's left to do is substitute 5 back into either of the original equations to find the y value of the point.
As for the second, you should notice that the second equation is simply the first with eqch term multiplied by -2. Divide both sides by -2 and you will have two of the same equation. Since they are the same line, any point on that line satisfies both and the system is therefore depenent.