I'll focus on problem 2.
For these types of problems, I recommend graphing the functions to see how the end behavior looks.
The graph of y = x^2 has a parabola where both endpoints aim upward. So each end goes to positive infinity (regardless if x is going to positive or negative infinity).
In short, the graph rises to the left and it rises to the right.
Increasing the leading coefficient will not change this fact. We can pick any leading coefficient we want and the end behavior will stay the same. All that matters is the leading coefficient is positive.
If the leading coefficient becomes negative, then everything flips: the endpoints will aim down. The other terms we add on (such as a 3x+3) will not change the end behavior. The leading term, with the largest exponent, is what directly and solely determines the end behavior.
The graph is shown below. I used GeoGebra to make the graph. Desmos is another handy tool you could use.