Yes, an enclosure will give you an external drive for backups and/or other storage.Can I buy a casing for it and use it like an external drive?
They wouldn't do that without notifying you first, giving you the opportunity to refuse the replacement. It's also highly unlikely that they would find a drive or memory that has been working to suddenly be incompatible.Just don't get rid of it.
When you send your Macbook Pro in to Apple for repairs, it's always a good thing to do it with factory parts installed.
If they deem your aftermarket memory or disk drive not Apple compatible then they will replace it for you and charge you for it.
They wouldn't do that without notifying you first, giving you the opportunity to refuse the replacement. It's also highly unlikely that they would find a drive or memory that has been working to suddenly be incompatible.
As all RAM and hard drives are non-Apple devices to begin with (since Apple doesn't make either), and both can be replaced without voiding the warranty or AppleCare, there is no need to keep the replaced parts, unless you have another use for them.Yes, they'll notify you. I wasn't implying that they're out to cheat you or anything. I'm just saying you should hold on to it just in case.
Who knows what they consider compatible?
As all RAM and hard drives are non-Apple devices to begin with (since Apple doesn't make either), and both can be replaced without voiding the warranty or AppleCare, there is no need to keep the replaced parts, unless you have another use for them.