Total PostScript Newbie Questions

I've just started learning PostScript and I'm going through a couple tutorials.  (I'm finding this frustrating since they either tend to take pages to get into things slowly or they assume I already know what they're talking about.)

I've copied and pasted the text from http://www.cups.org/documentation.php/doc-1.5/spec-postscript.html into a file and saved it as a .ps file.  I'm on the latest version of OS X (10.0.2).  I've installed Ghostscript, but that does not seem to display output and when I've tried to write to png files, I don't get output.  (I'm figuring Ghostscript must need a final "write to file" command to actually write to an output file, but finding a good Ghostscript command reference is hard.)

So for now I'm stuck using the built in Preview on OS X, and that may be part of the problem.

I've added this text:

% Add some text

/showGorilla % stack: x y ---

{ moveto (Gorilla) show }def

/Times-Roman findfont 6 scalefont setfont

72 300 showGorilla

/Times-Roman findfont 10 scalefont setfont

72 275 showGorilla

/Times-Roman findfont 15 scalefont setfont

72 250 showGorilla

/Times-Roman findfont 20 scalefont setfont

72 225 showGorilla

to the file I liked to above (I've included the full text at the bottom of this post).  It works.

But I have two questions:

1) The commands specify a 2" circle for the smiley face and it comes out to be 4".  Even in the picture provided on the source page, the smiley face circle appears to be about the same proportion (on the page) as I get when I view the file.  If I change the diameter of the circle to 4", it becomes an 8" circle.  Why is the size of all the graphical objects doubled when I view or print this file?

2) I was exerpimenting with rotate and added "90 rotate" before the word "Gorilla" is to be printed and the result was no text at all.  Then I put it in before the circle for the smiley face, but the only effect was that everything after wherever I put the "90 rotate" command was no longer visible.  What am I doing wrong?  Eventually I'd like to be able to specify, in the ps file, if I'm printing landscape instead of portrait and, from what I've seen, there seems to be no way to do that other than to use rotate and to set the page size accordingly.  Are there better ways to do that?

Here is the full file, with the text for writing "Gorilla" included:

%!PS-Adobe-3.0

%%BoundingBox: 36 36 576 756

%%Pages: 1

%%LanguageLevel: 2

%%EndComments

%%BeginSetup

% this is where fonts would be embedded

%%EndSetup

%%Page: (1) 1

%%BeginPageSetup

% this is where page-specific features would be specified

%%EndPageSetup

% Draw a black box around the page

0 setgray

1 setlinewidth

36 36 540 720 rectstroke

% Draw a two inch blue circle in the middle of the page

0 0 1 setrgbcolor

306 396 144 0 360 arc closepath fill

% Draw two half inch yellow circles for eyes

1 1 0 setrgbcolor

252 432 36 0 360 arc closepath fill

360 432 36 0 360 arc closepath fill

% Draw the smile

1 setlinecap

18 setlinewidth

306 396 99 200 340 arc stroke

% Add some text

/showGorilla % stack: x y ---

{ moveto (Gorilla) show }def

/Times-Roman findfont 6 scalefont setfont

72 300 showGorilla

/Times-Roman findfont 10 scalefont setfont

72 275 showGorilla

/Times-Roman findfont 15 scalefont setfont

72 250 showGorilla

/Times-Roman findfont 20 scalefont setfont

72 225 showGorilla

% Print it!

showpage

%%EOF