Yes, the Furrion Vision S Wireless RV Backup Camera System w/ Night Vision # FOS05TASF will work fine with your 2015 Keystone Bullet.
The only thing you're going to need to do is connect the camera to a 12-24V DC circuit using 18-AWG or larger cables. Also, the length of your trailer will not affect the compatibility or functionality either. view full answer...
Nope, you do not need to cut a vent hole open to install the Furrion RV Electric Fireplace with Logs # F30SW15ABL.
You just need to make sure you have nothing blocking the front of the fireplace where the air vents out, but otherwise you do not need a new vent hole. view full answer...
I believe I have highlighted the "E9" code you are referring to on your Primus IQ Brake Controller # TK90160 in the attached picture from the installation instructions.
The probable cause is that the trailer is connected and the brake controller loses connection to the battery ground. To remedy this you simply need to check your ground connections and make sure they are all secure and connected to a clean, bare-metal surface. Even some paint can cause an issue. Be sure to check the ground... view full answer...