In the first part, you have to see that condensation will occur when there are more water molecules in the atmosphere that "want to condense" versus the number of water molecules that "want to evaporate". If it helps, picture a rainforest which has a lot of water in the atmosphere, so the net movement of water will be to condense (some condensed water will evaporate, but MORE water vapor will condense). Thus, the partial pressure of water in the jungle is at LEAST as great as the vapor pressure at the given temperature.
Contrast this with a desert, where there is little atmospheric h2O, thus low atmospheric h2O partial pressure. More water will want to evaporate compared to the amount of water that is available to condense, thus there will be a net evaporation of water. Thus, condensation will NOT occur because atmospheric partial pressure is less than the vapor pressure.
The 2nd part of the question can be visualized as follows: water is boiling at a lower temperature, so it is "easier" to boil. Less energy input is required than normal, so there must be less pressure that is "holding down the solution" and preventing it from boiling. The higher the atm pressure, the more energy input is required to boil a solution. At 1 atm, the BP is 100C. So in the new case, the BP is lower, so atm pressure must also be lower.
