You can't really prevent drop eye. I remember reading several years ago in the aro forum that aros that were kept in ponds developed dropeye less frequently somehow than those kept in aquariums, though I don't know how much truth there is to that claim. I've also never heard of anyone having success with the "ping pong ball method" or anything similar. It's really just all up to chance and genetics; some specimens just don't develop dropeye, but most do.
And yes, you can feed crickets to an arowana, but they won't offer much nutrition. Best to stick with pellets and raw fish fillets/market shrimp.