Please help me with this Confidence Interval problems...

Q1) Using the sample size formula: n = [ P(1-p).z^2] / m^2 for a proportion, explain the effect on m of:

A) Increasing the confidence level,

B) Decreasing the margin of Error..

Q2) True or False-->The confidence interval for a mean with a random sample of size n=2000 is invalid if the population distribution is bimodal----why?

Thank you in advance!

Regards,