If the elongated spots on the edge of the leaves are blackish brown, its probably a result of not being watered - these plants do seem to require a fair amount of watering. You can cut off any badly affected leaves with impunity. I can't see any evidence of anything else currently on the plant, and they are prone to producing blackened areas on the edges of leaves if they're near a heat source or the air is very dry, or they've got a bit dry at the root. Misting regularly helps if the air is dry.
As for the stem in 2, ignore it - nothing's perfect, and the plant will sort that out itself, either by growing upwards normally, or dying back, at which point you can trim it off. You refer to yellowing parts - ignore those too, unless they completely die back, when you can cut them off.