To answer the white noise question - yes it can be a prop but it's a 'good' one in the sense it's easy to use, portable, and easy to wean by gradually reducing volume. Many people here use it for years so I wouldn't avoid using it because of prop worries. You can use it for naps and not nights, that's fine, many babies go to sleep differently during the day than they do at night.
In terms of day/night differentiation, just expose him to light in his (waking) daytime hours, don't let him sleep excessive lengths at a time and then at night keep things dark with minimal interaction even if feeding or changing. Usually that's enough for them to work it out
a simple bedtime routine before night sleep is also a good habit to start early - something like bath, feed, bed - which can then develop and change as your LO gets older to include things like teeth brushing and a story.
