You really should be using styles to do this rather than applying local formatting. That said, there is a lot of extra steps needed to process multiple paragraphs of various styles so I'll take the easy way out for the sizing step.
Code that adapts to the selection size goes along the lines of
Code:
Sub BulletsAndSizer()
Dim aRng As Range
Set aRng = Selection.Range
If Len(aRng.Text) > 0 Then aRng.Style = "List Bullet"
aRng.Expand Unit:=wdStory
aRng.Font.Size = 18
End Sub