Hi Austen (again ),
Not sure if you can control the msgbox features from within Excel. They are Windows properties. You can set it by going to your control panel -> Display -> Appearance, but that would change everything, not just a msgbox. Colo has designed something called ktMsgBox, which allows for manipulation of the msgbox environment. A download link is here, and it is an add-in.
As far as putting multiple lines, you can use quite a few things ...
Sub tesingForAusten()
MsgBox "This is line one of the message box." & vbCrLf & _
"This is line two here." & vbNewLine & vbNewLine & _
"We skipped a line and went to four." & vbCrLf & vbCrLf & _
vbCrLf & vbCrLf & "Thank you, Management.", vbInformation, "Hello"
End Sub
The vbNewLine is pretty self explanatory, but the vbCrLf stands for Carrige Return/Line Feed. You could use them seperately, but it's generally good practice to use them in conjunction.
Hope this helps Austen.