\documentclass[letterpaper]{article}
\usepackage{pdfpages}

\begin{document}

% you can specify the exact pages to include as well:
\includepdf[pages=2-4]{pdf_file_01.pdf}

% without "pages=-" it will only include the first page of the pdf file
\includepdf[pages=-]{pdf_file_02.pdf}

\includepdf{pdf_file_03.pdf}

You can also type text or \LaTeX \ in between included pdf files and that will just generate a new page for the content.

This is just some inserted text, that will appear on a new page between the inserted pdfs. Note that the margins are quite large. You can always adjust margins and text padding in latex, I am happy to show you how to do that or give you some example tex file. 

\begin{flushleft}
here is flush left text
\end{flushleft}

$$L(x)=\int_1^x\frac1tdt$$
$$E(x)=L^{-1}(x)$$

\begin{flushright}
here is flush right text
\end{flushright}

There are ways to overlay text on top of an included pdf using other \LaTeX \ packages such as Tikz.

The next page is just a printer test page I found online.

\includepdf{printer_test_page.pdf}

\end{document} 