Rate of change and limit of a function Unit questions

Hi there, i have a few precalculus questions that im not sure how to solve, if you can help that would be great!

1. For what value of the constant c is the function f(x)= x + c, x < 2

cx(squared) + 1 > and equal 2

continuous at every number?

2. Can a limit exist at a(a as in variable) even though the function is discontinuous at a? Explain, use a graph

3. A man has been travelling in a spaceship. The height, in metres, as it approaches the moon is given by h= 10t(sqd) - 40t + 40 where t is in seconds. When and with what speed does it land on the moons surface?

Thanks alot hope you can help

sqd= squared