Increment the section number with 1, not 0.1

Your used document class report starts sectioning with \chapter. Thats the reason where your 0. comes from. Change \section to \chapter or use document class article.

The big chunks of white space, especially in the table of contents of your changed MWE (to class article), you can solve with macro \raggedbottom in your preamble. The problem is that LaTeX stretches the white space between headings and paragraphs. It often ocurs with less text. With \raggedbottom LaTeX has not to place the last line of the page always on the same place.

The class report uses chapters as its top level sectioning.
(_{^{part >}} chapter > section > subsection > …)

If you only want to use sections as the top level you should use the class article.
(_{^{part >}} section > subsection > …)

In your example, you could add

\renewcommand{\thesection}{\arabic{section}}

to your preamble so that \section{} omits the 1. but this still produces typographically errors in the Table of Contents. It would be better to just use the class article.

If you want to keep the report document class and want the sections within each chapter to be numbered 1, 2, 3, etc rather than (if within Chapter 2, say) as 2.1, 2.2, 2.3, etc., you need to redefine the macro \thesection. For instance, you could issue the command

\renewcommand\thesection{\arabic{section}}

in the preamble.

Note that this will work even if you don't issue any \chapter commands at all.