The benefit of having a lighted front porch, is that when you look through the peephole you can actually see who is there.  A dark porch defeats the whole objective of a peephole.  A sensor activated light is an even better option, since it is energy efficient.

These days, sash locks come in both left-handed and right-handed versions, although the left-handed ones are more difficult to get hold off.  If you are unable to procur a left-handed one it is possible to improvise.  All you have to do is reverse the latch within the casing.  Get a locksmith's help, if you are unable to do it yourself.

If you have glass panel in your external door, it is safer to fit a deadlocking cylinder nightlatch instead of the standard type.