Where to tweak basic layout that isn't on the title page?

[SOLV-Code]

I'm trying to make some small tweaks to the layout of the main report body. For example:

• reduce the large top margin for every chapter heading
• reduce side and bottom margins

Are these specified in one of the 3 *.cls files in \cls? Or should I be searching through the _extensions folder?

Details below.

Chapter Headings

From the *.tex file I can see that chapter headings are created like this

\chapter{Community Summary}\label{community-summary}

Searching through the cls files for \chapter and {chapter} I find many instances, but the most promising seems to be the chunk below from krantz.cls, starting in line 652:

\newcommand\chapter{\if@openright\cleardoublepage\else\clearpage\fi
  \make@cornermarks
  \cleardoublepage
  \if@ChapterTOCs\if@filesw\immediate\closeout\@chaptoc\fi\fi
  \pagestyle{headings}%
  \thispagestyle{folio}%
\if@ChapterResetsPage\global\c@page\@ne\fi
                    \global\@topnum\z@
                      \gdef\chapterauthor{\@ca}%
  \gdef\endchapterauthors{\end@cas}%
                    \@afterindentfalse
                    \secdef\@chapter\@schapter
%%%                     \@ifstar{\@schapter}{\@trplarg{\@chapter}}
                     }


\def\@chapter[#1]#2{%
  \ifnum\c@secnumdepth>\m@ne
    \if@mainmatter
      \refstepcounter{chapter}%
      \typeout{\@chapapp\space\thechapter.}%
      \addcontentsline{toc}{chapter}{\protect\numberline{\thechapter}#1}%
    \else
      \addcontentsline{toc}{chapter}{#1}\fi
  \else
    \addcontentsline{toc}{chapter}{#1}\fi
  \chaptermark{%
    #2}%
  \addtocontents{lof}{\protect\addvspace{10\p@}}%
  \addtocontents{lot}{\protect\addvspace{10\p@}}%
  \if@twocolumn
    \@topnewpage[\@makechapterhead{#2}]%
  \else
    \@makechapterhead{#2}%
    \@afterheading\fi
  \if@ChapterTOCs\if@filesw\immediate\openout\@chaptoc\thechapter.toc\fi\fi
}
\def\@makechapterhead#1{%
  {\parindent \z@ \raggedright \baselineskip \z@ \lineskip \z@ \parskip \z@
    \vbox{
    \vskip -2\p@
    \ChapNumFont
%Remove comment if "Chapter"  word required before Number
%\if@chapnumonly\else
%    \@chapapp\
%\fi
    \thechapter
    \vskip -15\p@
    \chap@rule
    \vskip 6\p@
    {\baselineskip 20\p@\lineskip 20\p@\ChapTitleFont #1\par\vskip-15pt}%
    \noindent\hbox{\vrule height.5pt width84pt}
    \vskip28\p@}
            \if@ChapterTOCs
      \make@chaptoc
    \else
\fi
    \vskip 19.3\p@}
    \def\theequation{\thechapter.\arabic{equation}}}%

Am I looking in the right place?
If so, which specific bit controls the top margin? Is it one of the line skips?
If not, where should I go instead?

page margins

Where do I change those?