IPhone 4 :: Sleep / Wake Button Was Continually Stuck

I've just had my iPhone 4 replaced by Apple, as the sleep/wake button was continually becoming stuck in a rigid position.Â

Unfortunately, after the phone was replaced (and the data on the old handset deleted), I realised that - for some reason - my iCloud contacts were not up-to-date (I reckon I'm about 100 short). I'm missing key contacts from my phonebook.Â

However, when writing a text message on the new handset, I can click on the "To" field and start typing the name of contacts who were in the phonebook on my last handset (but not in the phonebook on the new one) and their name appears.Â

For example, the contact "Louise Thomson" is not in the Contacts app on the new handset, but was in there on the old one. However, when I start typing "Louise Thomson" into the "To" field of a text message, her contact details bizarrely appear, and I can send her a text.Â

Firstly, why is this happening? How are the details making their way onto the new handset, if they are not updated on iCloud? And, why are they not appearing in phonebook?Â

Secondly, and more importantly, how I can add all the contacts (IE the ones available to text) with a single click?Â