well I don't know much about real film, but you should check the internet. There are a lot of advices how to make your movie look more like film. Final Cut Express is 200 dollars (I believe) and has a lot of options, but you'll have to learn it. You can probably do some things in iMovie to.
What's the difference with film and digital? Film has compared to your consumer camera more contrast. Check youtube and such to see how to achieve this.
Film is more grainy, most people I know say they like this, but I think, I actually don't.
Film is "unlimited" HD. "pixels" of film are as big as the molecules representing a colour. That's why all the old films can be put on HD. Cause they were shot on film AKA very high definition. (what about digital effects I can hear you say, those where rendered in 2K from the beginning for theatrical releases, 2K is resolution above full HD).
24p isn't just the amount of frames, it also creates other pictures (so converting you files won't magically add that effect, you'll have to record in 24p. although making it 24p does help to make it more like film). Because of the less frames, frames are more blurred with movement. (or something like that, just search it up on google).