Well as far as the fraternity; it sounds like they are just jealous. You mentioned before that they are underground -- and you guys are not (from my understanding). So maybe it will just blow over. Being friends with the President is definitely to your favor. Perhaps he can work with you guys and have a mixer or joint community service event. I mean there is no real competition, so I don't really understand the ill-will. Again, hopefully it will just blow over.
As far as recruitment -- think about what your campus can offer you as far as facilities and advertise a pizza night or something similar. College kids
love free food! Make sure to make it RSVP or something just so that it won't get too crazy.
As far as committment, it's natural to get frustrated with low involvement -- but sometimes you have to give a bit in order to get anything back. For example, you can require attendance at an informational event -- but then afterwards leave to all go out together. Or offer incentives such as a 100% participation award at an annual formal. However, in the vary least, your sorority should set standards where if too many events are missed, the sister must go on some sort of probation period. Or maybe pay a fine (which is nice for the sorority's coffers ultimately
)
Also, as a group, try to be overachievers among campus organizations. Be active and visable with student activities and events for the general campus population. This will help instill a sense of pride and wanting to belong to your sorority. Although there's no easy recipe to get it, this unwavering pride is absolutely key to the success of any Greek organization.
Good luck to you!