You should find answers in a microsoft web site
in msword, this is known as "multilevel list", you will find exactly what you need here http://office.microsoft.com/en-us/word/HA100650171033.aspx
I just tried ms word office 2007 using "menu:paragraph->multilevel list", there is a list library with the style you are asking for.
To renumber, select the number, right click and set the start number, or select them all, and set them to continue the previous one.
you can also swap horizontally the numbers and the text by defining a new number format and select a left/right alignemnt for the number (left of the text, right of the text)
You can also define the right style for your paragraphs and then apply the style to the existing text, so numbering will be consistent with the rules you define and all the text you use wil have a consistent numbering as you require.
From http://office.microsoft.com/en-us/help/HA010873051033.aspx Ms Word use a very primitive regular expression syntax. Note that the replacement will not work in numbers automatically handled in the styles. see above how to do it. A regular expression will not modify the characters generated by word.
^H then click on more >> and cross "use wildcards"
then enter the following expression ("find what")
([!^13]@)([0-9]@)
and this one ("replace with")
1.1.\2 \1
And then use next/replace where appropriate.
This changes the following text
abcdefgh 1
lksdjgkfljg 2
ksdjlfksdj 3
into
1.1.1 abcdefgh
1.1.2 lksdjgkfljg
1.1.3 ksdjlfksdj
I hope it answer your problem.