the "TER mobile" app by sncf is the official french railway one, and is great for timetabling information. you can also find paper copies at the ticket office, but they're a real problem to get folded up once you've looked at them
the staff at both nice ville and monaco stations are really helpful and the staff on the platform will all speak english if you're not comfortable with french.
google maps has only the top monaco-monte carlo station entrace on - there's actually at least 4 ways of accessing it. the best way for the harbour is to use the st devote exit. they're all listed
here but for some reason you only get to look at one of them, and the fontvielle/rocher one for the rascasse end of the circuit isn't on streetview because they haven't reimaged for 7 years...
between the top exit of the station (on google maps) and the lower end at st devote is around 25 storeys, so if you're not a triathlete it's worth using the station escalators and lifts (which is all free access, no barriers) to get around a bit
there's some public lifts which to be honest are of limited use but can be fun to explore the place with.