You need to distinguish between Section breaks and Page breaks. The former carry margin formatting. Section breaks can be set to begin the new on an even or an odd page. This will result in blank pages in some circumstances.

You need to use Styles for formatting changes to fonts and formatting size and color.

Headers and footers may have left and right indents that are outside the margins. They can also have tab settings outside the margins. Distinguish between indents and margins. They are different concepts in Word. Margin changes are rarely needed. Page numbers are almost always in headers or footers.

Sections / Headers and Footers in Microsoft Word 2007-2013
Understanding Styles in Microsoft Word

For a good background in using Word, try the series of pages beginning with:
Basic concepts of Microsoft Word: An introduction by Shauna Kelly

The time you spend going through these references should be saved very quickly.