The first part can easily be achieved using
Document Batch Processes with the following custom process. The second part would require more information about what to look for and what to replace it with.
Code:
Function FixTable(oDoc As Document) As Boolean
Dim oTbl As Table
Dim i As Long
On Error GoTo Err_Handler
For Each oTbl In oDoc.Tables
For i = oTbl.Rows.Count To 1 Step -1
Select Case i
Case 2, 3, 4
oTbl.Rows(i).Delete
Case Else
End Select
Next i
Next oTbl
FixTable = True
lbl_Exit:
Exit Function
Err_Handler:
FixTable = False
Resume lbl_Exit
End Function