We are working on getting our software working with the Jessie. There are a couple things which we are still working on like noVNC which is still facing some problems on Jessie. VNC does work but noVNC does'nt.
All the functionality in our image is based on the script here: https://github.com/DexterInd/Raspbian_For_Robots. If you want to try this, just clone the directory on /home/pi/desktop and then move the update_backup.sh to /home/pi and run it which will make the icons on the desktop and then run the DI software update from the desktop to install everything. However this is still in development for Jessie and you should only try this if you are fine with bugs which would be there. If you go this way, it would be great if you could send us some updates about the problems you face and any solutions too.
The scratch GUI might be a bit complex to explain and the main script does that too. It is pretty custom built for our image so we did not publish a lot of documentation around it because it is more or less bound to cause problems with other images unless they get the environment created by the Raspbian for robots image.
Right now we are working on getting all these issues sorted and I think you would run into the issues too when you are using your own image with all the software that we have built for Jessie. I think the Jessie image would be ready in a few weeks but no ETA yet, however this is our highest priority right now. If it takes more time that would most probably mean that they are more difficult bugs to squash.
The robot web server error seems to be coming becasue raspberry_pi_camera_streamer is not installed on the Pi. Did you run this script on the Pi https://github.com/DexterInd/GoPiGo/blob/master/Software/Python/Examples/Browser_Streaming_Robot/browser_stream_setup.sh and check that it finished properly.
We'll look into making option 3 a bit more descriptive for people, but that option is mostly for people who don;t need things like GUI and are happy using the terminal and comfortable with tinkering scripts and linux in general. We usually spend a lot of time in making sure that our image works for almost everyone with every kind of usecase. It also makes it a lot easier for us to help out people who are having any troubles.
Bluetooth is also on our list of things to test with the jessie image but I am 100% sure that we would be releasing it before your demo. So might have to use your own image if you want to use onboard Bluetooth. We have tried using Bluetooth on the B+ and Pi2 with one of the projects and an external Bluetooth adapter. You can go that way if all you want to do is use bluetooth.