As for your camera flash settings, I don't have an answer, you'd better ask that on the Olympus users forums., Anyhow you might consider also getting a simple radio trigger like the YN602/3 to help you control your flash without using their optical slave senssors.
As for flash units:
for about 50$ you could get two bargain flash units MK930 or YN460II reviewed here, they both are about the 40GN mark.
Another options for the same price, is getting th "old" and popular YN560, that somehow still sell on some shops (saw it on thegadgetphoto) for about 50$ and are 1 stop more powerful (~50GN)
DIY photography stuff for product photography and