Experience with Ethiopian ADD
 

Tight connections at ADD are very do-able... So long as your inbound is on-time you should have no problem. If the inbound is delayed or connections are tight, ET often has staff waiting to whisk you off to your next flight. Seeing as how you are going to the USA though, you probably won't be able to skip the security checks as I have often seen happen on North America/EU to Africa connections. The North American flights are usually sectioned off in their own area with a couple gates (3 of them maybe?) which makes it a bit easier as there are fewer passengers to process and they can easily move you through to the front of the line if needed.

If you have *G status you will have a dedicated security line and dedicated document check counter, which takes no time to go through.

The JRO flight will have a lot of folks making connections. I would just try to get a seat near the front for deplaning and, if parked at a remote gate, try to get on the first bus to the terminal.

Plat as in Platinum status on a Star Alliance partner? (guessing United) - If so, then you would also be eligible for the separate line for *G/Cloud Nine (business) passengers

The one hour connection is very doable. I travel often through ADD with tight connections. The staff will meet you as you disembark from the plane and make sure you get on your connecting flight. No worries. The baggage will also reach your destination with you.

These super short connections are actually one area I find that ET shines. As long as your plane is on the ground before the other flight closes its doors (which seems to never be right on time) then you'll make it. I've been the beneficiary of their service twice since the (former) NRT-HKG-ADD flight was perpetually late. But even times when I had plenty of time to connect, I always saw the ET staff meeting the plane to whisk people off on short connections, typically they'll either have a sign for your destination and/or be shouting it as you exit the plane.

It's been a while since any news about the airport expansion / new terminal building... Is ADD still the same old?

expanded and new terminal is operational. however, old terminal is still in use and that is where transit security is.