Ok, deep breaths
@kellie_jane. This could all be nothing to worry about.
The police check doesn't come back with the adresses. It just says whether there are any spent or unspent convictions. That's it.
Now, the middle name. Where was the error made. In the original eDV entry or on the DS260? If he ommitted it on the eDV but corrected it on the DS260, that should be fine. I was the derivative and missed a middle name on the original eDV but corrected it in the DS260 and it was not an issue. If he missed the middle name on the DS260, that will be resolved when the CO looks at his birth certificate. Shouldn't be an issue.
Re the addresses, this may not be an issue. As long as he listed the address, you have some flexibility on the dates. I know I guessed some of my dates, as did my husband (he moved houses each year during university) and we were all good. They want to know the addresses from a security perspective (i.e. they want to know if you spent two years in the depths of Afghanistan with the Taliban, because that will kick off additional security checks at KCC).
Don't stress. Easy for me to say and, when I was in your position before interview, I stressed like a mofo, but I think you're golden.