Assuming you only want to test font sizes and typefaces from the first heading onwards, you could use code like this
Code:
Sub CommentMania()
Dim aRng As Range, aPara As Paragraph
Set aRng = ActiveDocument.Range.GoTo(What:=wdGoToHeading, Which:=wdGoToFirst, Count:=1)
aRng.End = ActiveDocument.Range.End
For Each aPara In aRng.Paragraphs
If Left(aPara.Style.NameLocal, 7) <> "Heading" Then
If aPara.Range.Font.Size <> 10 Then
ActiveDocument.Comments.Add aPara.Range, "Check font size"
ElseIf aPara.Range.Font.Name <> "Arial" Then
ActiveDocument.Comments.Add aPara.Range, "Check typeface"
End If
End If
Next aPara
End Sub