Yeah, find the oil leak and fix it. Are you really expecting people over the Internet to tell you where an oil leak is? It could be the HG, cam seals, front main, VC, pressure switch, etc.

Get up in there and look. If it is all nasty, spray the bitch down with some degreaser or brake parts cleaner and start fresh.

As for the misfire you have not checked all your components in the ignition system. As posted above the coil pack can fail. Replace that with a known fuctioning one.