Hello Jean Pierre,
Monarch will let you encrypt an XLSX file, but I don't think it will let you lock individual columns. You might find the Monarch Context plugin for Excel useful - this lets you include a locked version of the original report that is linked from the cells in the table sheet. Datawatch sales should be able to give you a web demo or let you try it.
For screen scraping I'll defer to Grant - he's got previous in this area.