"Bomb" Replacement and Pentosin Flush

["Christopher Ritchie" <cjr1@gte.net>]

The Parts Connection has pressure accumulators ("bomb") on sale this week. 
Good price - I checked around.  Will do the job this weekend, my first.  I
also want to replace and flush all the hydraulic oil because the PO topped
it up with power steering fluid.  No leaks yet.  Queries:

1.  What is the size of the crush washers on the banjo fitting on the bomb?
 Are those the only ones  needed?  It looks like the only pressure fitting
being removed is the line from the pump to the bomb.  Are they Audi dealer
parts, or can I get them at a Pep Boys?  I would buy a whole selection of
them to have if someone could recommend where I could get them.  

2.  How do you flush the system, especially the steering and pump portions?
 I will drain and clean the reservoir and mesh filter while replacing the
bomb.  How do I get the rest of the old contaminated hydraulic oil out? 
Then, how do I flush some fresh Pentosin through and completely drain?  

The Bentley has the replacing procedure on page 48.14.  It states:

a)  fill the reservoir to the "MAX" mark and turn the steering wheel lock
to opposite lock with the engine off.  Are they assuming that I previously
drained the reservoir of the old fluid?  What does turning the wheel do? 
If that expels old fluid in the steering, where does it go?  How would new
fluid be sucked in from the reservoir if the engine is not running?

b) then the Bentley states to top up again; start the engine; and, keep
adding fluid.  Should I drain again after turning the steering lock to lock
and before starting?  I assume you do all this with the new bomb installed.
 I also assume that the engine should not be started with the bomb out or
any part of the system disconnected.  But how is the old fluid in the
steering flushed from the system if it has been closed throughout this
procedure?

3.  Are 2 liters (of the synthetic stuff) enough?  I want to meticulously
flush this system since I have some power steering fluid in it and I am
going to synthetic fluid.  With the age of this car, the existing fluid is
probably mineral.  I realize that mineral and synthetic should not be
mixed.  

TIA.  Sorry this turned out longer than I originally thought.