If I don’t have any permanent unit awards, do I wear my current ones for my DA photo? Does my regimental affiliation have to be on my ERB?

You only wear unit awards when assigned to the unit or if you were a memeber of the unit when it was earned, and you were part of the action awarding it. Thank you for your service.

You will need to wear current units awards. As for the regimental affiliation you have a few choices. Now you can affiliate with branch specific or any unit you have successfully served in.

Unit Citations: A definite 'NO' to your Unit Awards unless you were there during the awarded dates.
I was present at 2 different units that received the Meritorious Unit Citation, so I have it with an oak leaf cluster.
"A unit award is given to an operating unit and is worn by members of that unit who participated in the cited action. Personnel who did not participate in the cited action, but who are assigned in the cited unit, are authorized temporary wear of some unit awards."

Regimental Affiliation: Yes to your Regiment. I'm retired and so it was when I was still active. If my memory is correct from our day room brief by our S1, there were several reasons.
1. You couldn't change it once you affiliated. It was a permanent 'assignment' requiring a DA form submitted and signed by the individual their-self to change their affiliation.
2. Once DA saw the unit was 'filled up' with a certain percentage, any new requests would assigned to a unit to which the soldier had served, particularly if they were a non-cohort soldier. DA would do this after the unit being requested (I don't what %) reached a certain percent level. I later heard cohort soldiers were almost always assigned to their cohort companies regardless - they had volunteered to be that unit when they had come into the Army.
3. When it was originally implemented, our S1 really wanted all of us to check our present duty assignment. One soldier wise-cracked that he didn't want to waste his time since he was ETSing. A week later when he was clearing installation he informed me that he had gotten a regimental affiliation of 'present duty' assignment.

Hope this helps. I am checking regs now, since things may have changed since I retired in 93. I will let you know when I find the current update.
CSM Mike Maynard on this site has a previous post about this and is probably person to best to ask.