I would have more rock in there, but it doesn't have to all start as live rock. You can add some dry rock and it will become live rock. I use Feller Stone's Antique Coral to supplement live rock.
If you added another powerhead point it behind the rockwork. Flow around the live rock will keep it working as a filter.
In a reef 80% of your filtration will be the live rock, the other 20% is from your skimmer and refugium. If you are willing to add something a HOB
refugium would be the most valuable IMO
. I am assuming the skimmer is a HOB
as well. If you have or added a sump for the fuge that would be even better, but not essential.
You can definitely keep the tank going as is but water changes are vital. 10% weekly is the ideal water schedule for reefs IME. If you have ANY problems do water changes more often, not larger ones. When I came back from vacation a couple years ago my reef was covered in algae. I did daily wter changes for a week and it got the tank back where it needed to be. Use RO
water and a good salt (I use Tropic Marin, but not the Pro Reef).
How do you do water changes at this point? What water are you using? What salt? How much? How often?