[OS X Emacs] Error messages

[Edward M. Roche]

Does anyone know how to interpret these messages:? 

1. From latex "output" window.
=======================
Running `LaTeX' on `testletter' with ``pdflatex  -interaction=nonstopmode "\input" testletter.tex''
/bin/sh: pdflatex: command not found

LaTeX exited abnormally with code 127 at Tue Jul  1 14:55:09
/

2. From "Messages" window
======================
("/Applications/Aquamacs Emacs.app/Contents/MacOS/Aquamacs Emacs")
Source file `/Applications/Aquamacs Emacs.app/Contents/Resources/site-lisp/site-start.el' newer than byte-compiled file
Loading prestart plugin files ...
Loading /Users/eroche/Library/Application Support/Aquamacs Emacs/site-prestart.el (source)...done
... done.
Loading easy-mmode...done
Aquamacs Mule installed.
Loading encoded-kb...done
Loading easymenu...done
Loading jka-compr...done
uncompressing tree-widget.el.gz...done
Loading cl-macs...done
Loading /Users/eroche/Library/Preferences/Aquamacs Emacs/Recent Files.el (source)...done
Cleaning up the recentf list...done (0 removed)
Defining fontset: lucida11
Defining fontset: lucida12
Defining fontset: lucida13
Defining fontset: lucida14
Defining fontset: monaco11
Defining fontset: monaco12
Loading /Applications/Aquamacs Emacs.app/Contents/Resources/site-lisp/edit-modes/tex-site.el (source)...done
Loading /Applications/Aquamacs Emacs.app/Contents/Resources/site-lisp/edit-modes/nxml/rng-auto.el (source)...done
Loading plugins ...
Loading /Applications/Aquamacs Emacs.app/Contents/Resources/site-lisp/site-start (compiled; note, source file is newer)...done
... done.
Loading /Users/eroche/Library/Preferences/Aquamacs Emacs/customizations.el (source)...done
Loading /Library/Preferences/Aquamacs Emacs/Preferences.el (source)...
Loading /Applications/TeXniscope.app/Contents/Resources/txs-search.el (source)...done
Loading /Library/Preferences/Aquamacs Emacs/Preferences.el (source)...done
Loading /Users/eroche/Library/Preferences/Aquamacs Emacs/Preferences.el (source)...
Restarting server
Loading /Applications/TeXniscope.app/Contents/Resources/txs-search.el (source)...done
Loading /Users/eroche/Library/Preferences/Aquamacs Emacs/Preferences.el (source)...done
Added to /Users/eroche/Library/Preferences/Aquamacs Emacs/customizations.el
Mark set [2 times]
Loading /Users/eroche/Library/Preferences/Aquamacs Emacs/frame-positions.el (source)...done
Mark set
Aquamacs is based on GNU Emacs 22, a part of the GNU/Linux system.
It is Free Software: you can improve and redistribute it under the GNU General Public License, version 3
or later. Copyright (C) 2008 Free Software Foundation, Inc. (C) 2008 D. Reitter. No Warranty.
1.4 is the most recent Aquamacs version available.
Aquamacs is based on GNU Emacs 22, a part of the GNU/Linux system.
It is Free Software: you can improve and redistribute it under the GNU General Public License, version 3
or later. Copyright (C) 2008 Free Software Foundation, Inc. (C) 2008 D. Reitter. No Warranty.
Loading latexenc...done
Loading tex...done
Loading latex...
Loading edmacro...done
Loading latex...done
Loading font-latex...done
Applying style hooks...
Loading /Applications/Aquamacs Emacs.app/Contents/Resources/site-lisp/edit-modes/auctex/style/german.elc...done
Applying style hooks... done
Sorting environment...
Removing duplicates... done
Loading tex-bar...done
Mark set
Loading tex-fold...done
Loading bib-cite...done
Loading reftex...done
Loading reftex-auc...done
Loading reftex-dcr...done
Automatic display of crossref information was turned on
Loading preview...done
Applying style hooks... done
Applying style hooks... done
Sorting environment...
Removing duplicates... done
Mark set
Wrote /Users/eroche/Documents/Barraclough/Letters/akletter-new/testletter.tex
Press <A-S-return> to exit full screen editing.
Type `C-c C-l' to display results of compilation.
LaTeX: problems after [0] pages.
(New file)
Applying style hooks... done
Sorting environment...
Removing duplicates... done
Mark set
Applying style hooks... done
Wrote /Users/eroche/Documents/Barraclough/Letters/akletter-new/_region_.tex
Wrote /Users/eroche/Documents/Barraclough/Letters/akletter-new/prv_testletter.ini
Type `C-c C-l' to display results of compilation. [2 times]
locating previews...
Type `C-c C-l' to display results of compilation.
error in process sentinel: preview-reraise-error: LaTeX found no preview images
error in process sentinel: LaTeX found no preview images
Type `C-c C-l' to display results of compilation.
LaTeX: problems after [0] pages.