Designing styles for complex, inconsistently-formatted multilevel numbered list

I hope to create template for a complex multilevel list.

I do not understand the best way to create and/or apply styles efficiently:


1 Heading Level-One (e.g. 16pt font; 12/3 paragraph spacing)
   Plain text, indented to match Level-One

2 Heading Level-One (16pt font; 12/3 paragraph spacing)
   2.1 Term Bold-Faced  Definition regular-face paragraph indented 0.5" more than heading level
               definition regular-face paragraph indented 0.5" more than heading level
   2.2 Term Bold-Faced  Definition regular-face paragraph indented 0.5" more than heading level
               definition regular-face paragraph indented 0.5" more than heading level
3 Heading Level-One (16pt font; 12/3 paragraph spacing)
   3.1 Heading Level-Two (14pt font)
      3.1.1 Plain text, 12pt, indented to Level-Three
      3.1.2 Plain text, 12pt, indented to Level-Three
   3.2 Heading Level-Two (14pt font)
      Plain text, indented to Level-Three
   3.3 Plain text, 12pt, intended to Level-Two


I need to find a way to efficiently apply continuous numbering to an inconsistently formatted set of headings and variously indented paragraphs of plain text and heading text.
I have little trouble doing this by applying direct formatting, but I do not understand how to do it with STYLES - so it can be applied consistently across many document files.

Insight would be greatly appreciated. Thank you!
-sols