hi Pigletguinea (great name!)
It's the date lodged, not date CO assigned - though for partnership applications, you do tend to get a CO within 2 weeks, so it's not that much longer.
Your Kiwi hubby will need a full ACPO for the UK, as well as for any other countries he's lived in for the last 7 years (I think it was 7..). I don't remember needing to provide proof of addresses though?
I don't know about forwarding police certs after application, but my CO did request more info about an incident listed on my Kiwi hubby's Australian police check a couple of weeks after the application was lodged. I presume that they would also follow up any missing documents, but you do tend to get a time frame within the info must be received (usually 1 month from the date requested, based on my experiences with medical referrals).
Hope that helps!