Most of reviews app allow color, fonts customization, etc. and the app will not send automatically email, if you don't configured them to do so.
Regarding hiding 0 reviews, some apps have this option, other not, but you can achieve that easily with few lines of code (at least is what I did for example using Stamped.io Reviews App)
I am using Stamped.io Reviews app
Disclaimer: I am not affiliated, just personal opinion based on my experience with various store.