Question

Is this true about slopes Change in the dependent variable relative to change in the independent variable

Answer 1

Yes, yes it is true!

Answer 2

Yes.
                                                              change in y     change in dep. var.
Remember the slope formula?     m = ----------------- = -------------------------------
                                                              change in x       change in indep. var

Remember that y is usually chosen to represent the dependent variable and x to represent the independent one?