So I was wondering if somebody could help me on how to start #1 and #2. In general, I'm having a lot of trouble with diodes. For example, on number 1 do we first assume that one of the diodes is off and the other is on? Any help would be appreciated.

 

Usually what you do is figure out the transfer characteristic. So assume that you have a DC source instead of the AC source and that you are going to slowing increase it from a sufficiently large negative voltage to a sufficiently large positive voltage. In this case, "sufficiently large" can be anything more than abot +/- 17 V since that is the peak voltage of your AC source.

Then determine what the output voltage is as a function of the input voltage. You do this my starting at -17 V and determining which diodes are on or off. You then consider at what input voltage one of the diodes will change state. Between those two voltages you can reduce to the circuit one with no diodes (replacing each diode with an open or a short as appropriate). Once you get to the next breakpoint, you repeat the process. You keep doing this until you get up to +17 V. At that point, you are in a position to map each point on the input sinusoid to it's corresponding output voltage.