Re: cold rattle
If you ran low on oil then there was a chance of excessive wear and damage on any of the moving parts inside the engine. Sorry to break it to you.
However a cold rattle at startup is the tell tale sign of the variator. It tends to go on for longer the more worn the variator gets. So if its very worn it could rattle all the time or settle down once the engine gets warm. It's also got a distinct diesely noise about it, and can be heard quite high up on the engine. If it sounds like some other knocking then I would be a bit concerned.
To err is human, but you need an Alfa to really screw things up!
The road to heaven is paved with old Alfa's.