Troubleshooting Electrical Circuit Problems?

My wife and I are renting an upstairs apt from my parents who insist everything is in excellent working order, but I am firmly convinced that we are sleeping in a potential fire trap. A while back my step dad (no electrical experience) put in a motion light switch at the bottom of our stairs. Then we started noticing that when we turn our ceiling fan off via a horizontal slider switch inside the apt, the downstairs light would turn on.

Then 1 plug of a 2 plug GFE in the bathroom went on the fritz. It couldn't power any device that had a heavy current draw like a space heater, but it would still power things like night lights and a floor lamp. Then the CFL bubble in the kitchen started having issues with igniting the CFL tubes inside which gradually ended with a complete failure to turn on. We replaced the 2 curved tubes inside, thinking the bulbs burned out, but it still won't turn on. My parents insist there is no possible way the ballasts went bad unless we were having light switch raves all the time. Then today my wife hears one of the wall plugs on the other side of the house is making faint crackling and humming noises; she ended up banging her hand on the wall and the noises went away.

So please tell me if this apartment is a lit cigarette waiting for someone to fall asleep and burn down the house or if my parents are right and I'm just being "paranoid", as they say!