When guests book a listing, they don't have the option to choose whether they want to book the listing as instant book or request to book. This is set up by the host only. Whatever the option the host chooses on how the guest will book their listing, is what the guest will follow.
On the website, their is really telling the if the listing is instant book or not, unless the guest either use the instant book filter or on the final page of the booking process where guests pay and confirm. Instant book will show as reserve, while the other option will show as request.
Now, reviews can definitely affect bookings for both guests and hosts alike. But, guests can only see the reviews of other guests for your listing, and vice versa. Guests will not see the review you left for a guest as a host, only other hosts can see that.