She's talking aggressive for saltwater, they are nothing near the aggression level of Africans, especially elongatus! Think tiger barb aggression or a little less. I had about 10 (5 blue, 5 yellowtail) in a 75 with no issues.
Since you only have two pieces of rock I think you'll be good. The damsels are more open water, they are reef dwellers but they aren't afraid to venture from the rocks.
If I were you I would do 5 fish:
1 blue damsel
1 yellowtail damsel (buy these at the same time and first)
1 small clown (true percula or ocellaris are the smallest usually available, but I think tomato clowns are very nice too)
1 green clown goby
1 purple firefish
With those five you would have very easy to care for fish and all primary and secondary colors represented: red (firefish and clown), orange (clown and clown goby), yellow (damsel and firefish), green (clown goby), blue (both damsels and a little on the firefish), and violet (the firefish).
None of those exceed 3", are hardy, and together will cost between $50-$100 (very cheap for a complete stock!!