Firefish are also jumpers, and honestly I think a smaller wrasse could be a good choice. 2 or 3 benggai cardinals would probably be the best choice out of your list, they are peaceful and like to group together.
Also, you have a 30 g tank with a pair of clowns (which is fine). 2 clowns, 2-3 cardinals, and 1 wrasse (or a better choice would be a nice goby) would be a nice mix and would pretty much leave you maxed out for fish. I'm only recommending 5-6 fish because you have a sump with extra water volume, and I wouldn't recommend more than that amount in total.
If you like wrasses, I had a similar fish in my 14g biocube and it did very well for over a year...a twin spot hog fish. It is like a smaller, peaceful wrasse that is yellow with two spots. It was very active, and got along with my clown fish fine. I lost it unfortunately due to power outages from hurricane sandy =( I would definitely recommend one though
Best of luck!