Corrected entry: When you kill a boss or a mini boss, if they fade away after they die you won't face them again in the game, if their corpse remains on the floor, there'll be another encounter with them. (The garador, el gigante).
Corrected entry: Just before the boss battle with 'it' in the hanging cages, you first come across the monster on a ledge, and then you're instantly transported to the suspended hanging cages, with absolutely no indication of how.
Correction: This is untrue. There is a cut-scene directly before the boss battle in which Leon is ambushed by said boss and is thrown back towards the rig. Although we never see him hit the rig exactly, the boss is evidently powerful enough to break through a stone wall to get to him, throwing him from the ledge to the cage shouldn't be a problem. It's also possible that Leon jumped to avoid the boss' attack in the first place.
Corrected entry: Throughout the game, the Los Illuminados attempt to abduct Ashley from Leon, since she is the key to their plan, but in certain areas they'll actually attempt to kill her. This is most noticeable where there are chainsaw maniacs, the giant drilling machine trap or the armaduras that Ashley encounters while trying to reach Leon.
Correction: They have no doubt been instructed to capture her alive, but most of them are hardly coherent enough to obey commands.
Correction: Not true both halves of Mendez stay right were they are, and if you can kill the right hand without the liquid nitro he remains as well.