If those are the only plants you are planning you won't need ferts. The fish and fish food will provide all they need. Is there a reason for the "too much light" question (eg algae, BBA)? Anubias in my tank do best in very low light - the top of my tanks are usually covered in floating plants. 5-6 hour per day is not too long - but if there is too much light you could try reducing the inensity. If your lights are LED you can find cheap dimmers on Amazon that will fit the plug I can see behind the tank.
I can't see how the tank is placed in the room but you could also use black card to cover the sides and back to reduce the amount of daylight entering the tank