Q1 - I said expression in textbox and then I provided an example without criteria, try it: =[Field1] & Chr(13) + Chr(10) + [Field1]
Q2 - explore Conditional Formatting of textbox and combobox https://support.office.com/en-us/art...5-44E43B05E22F
Q4 - this could get a bit complicated and more than one way to structure the code which depends on what you want to happen, something like:
Code:
Sub someButton_Click()
Dim strMsg As String
Select Case Opt1
Case 1
If IsNull(Me.Field1) Then
strMsg = "Email"
Else
'code to send email
End If
Case 2
If IsNull(Me.Field2) Then
strMsg = "Address"
Else
'code to print letter
End If
Case 3
If IsNull(Me.Field3) Then
strMsg = "Phone"
Else
'code to do something else
End If
End Select
If strMsg <> "" Then
MsgBox "Enter " & strMsg
End If
modify as appropriate for your situation
Q5 - Validation Rule property like: <= Date() Or Is Null