The brake lines from the master cylinder generally go into a metering block
(has the brake warning light switch if the rear and front brake systems have
a large difference in pressure between them).  This block may have valves
that do not flow fluid unless the pressure is a particular positive value.
This prevents vacuum in the lines that could suck in air or water.  You need
full brake pressure to get fluid through here or blow fluid through the
system after this metering block.

The switch below the steering column is to turn off the wiper blades.  I
hope I am remembering correctly, but the blades will not operate unless the
vacuum operated door is open.  This prevents major damage if the blades were
to operate with the door closed.  Once the door opens, there is a switch
near the firewall on the engine side that powers the wipers.  In case there
is a vacuum problem, the wipers may not turn off.  This is what the under
steering column switch does.

Vito

Some issues you might have to do with the brakes.

- New calipers will eventually do like the old brakes, as the cast iron pits
form moisture buildup due to lack of use and then they leak.  Stainless
steel sleeved brake calipers work better.

- Master cylinders often need to be bench bled.  The rebuild kit has
instructions for this.  Basically, you take a hose from the output port and
stick the other end in the reservoir so that as you pump the MC, it blows
bubbles in the reservoir.  When the bubbles quit, it is bled.

- Set up of the master cylinder plunger is critical.  There is a threaded
adjustment that allows you to place where the plunger fits in the MC before
it depresses the piston. It must NOT depress it when you are at rest with
the pedal.

- Blowing through the lines is often not possible since you have a
proportioning valve in the lines.  These are not true proportioning valves
in that they regulate the pressure to the rear, but rather a balance system
so that if you lose pressure on one circuit, a piston slides and closes that
circuit so that pressure stays on the other.  When you applied pressure to
one circuit only (rear), you may have closed this valve and thus nothing
flows.  Some valves will reset but others have to be reset manually.  I do
not know what your car has.

The switch under the steering column between the headlight and wiper
override switches is the parking switch for parking the wipers in the up
position for changing wiper blades.