Is it necessary or do you think it's a good idea to make a separate pile of copies of all supporting documents to send in with originals for spousal visa?
Also. What it the best way to package the documents? I hear they don't like staples and paperclips but I don't know if that's true.
Also what is best. A slim box or a padded envelope?
You should include copies of anything that you want returned.
It's also a good idea to make a copy of the whole package for yourself. You will find this really useful when the time comes for the next visa application.
Don't use staples or paperclips. They will only have to be removed. Organize your package in a logical order in two piles, originals and copies and use rubber bands or string to secure.
I don't suppose it matters much what you send it in. When I mailed ours, the UPS store provided one of those plastic, non-padded envelopes.