High voltage power supply
Split the circuit into two parts:

1.



2.



Each of those will function by itself.

Figure out what 1 does (that's the tricky one.)

Then imagine feeding the output of 1 into the input of 2.



Figure out what the waveform looks like at the output of section 1.

Once you have that, you'll know the answers to the two questions you posed.



Both sections are common circuits that have names.  I'm sure you'll recognize the second section.

The first goes by a couple of names.  I'm not going to give you the names because the point of the exercise is for you to figure out how it works.  If you know the names, you could look it up instead of figuring it out.

The whole thing together also has a name.  Again, though, if I told you the name it'd spoil the point of the assignment.