New evidence is fine but if there was no mention of the impairment previously, then would you be amending your Alleged Onset Date? With an OTR it must be a Fully Favorable Decision, so they can't set a different Established Onset Date.

Similarly for the hearing you can add a new impairment but if there is no medical evidence previously, it might effect the EOD. The ALJ will first determine if the original impairments will allow an approval or not.

DDD would be unlikely to meet a Listing prior to a hearing, but there is a chance you could be approved via the Grid. Or, it could be determined both impairments equal a Listing.

Even approaching advanced age, education and skills are still a factor. Registered nurses or many with sedentary desk jobs, for example, struggle to be approved via the GRID even after age 55. Link: Sedentary Work Grid Rules | Maximum Capacity Sit Down Work

I know you thought early on the Grid was a factor on your first denial, but you were denied because they claimed you could still perform the same type of work, which means they didn't proceed to factor the Grid. You may have understood this later, but I just wanted to clarify.

There are fine points to each strategy for approval, which there is plenty of time for you to learn, but I would not give up on trying to prove you meet the COPD listing which should maximize your benefits.