Build online school conferencing system

I am looking to build a online school web conferencing platform. The objective is that students and teachers can log into tier respective classrooms and be in a virtual classroom where the students can see and hear the teacher, share a whiteboard, and teacher can see, hear, share whiteboard with students and have option to place students into break out rooms for study sessions. The teacher would have the ability to give co/presenter permissions to a student to ask a question, draw on white board etc. The system should be able to withstand up to 800 people at once. Students and teachers should be able to login using a link that we generate and no installation should be necessary, the link would have the username and password embedded. I have listed the features in the attached excel document. However, the objective is to be able to copy a similar system that we are currently using, but because there are some flaws we would like to create our own system for this. For a link to see the teacher and student environment we are currently using, please message me. I would like to implement every feature that we currently have on our current system. I understand that there are generally 2 ways to approach this: 1. Desktop based driven by java 2. Web/browser based which uses ajax, java/flash etc. either way, its important that this works cross browser, and on windows and mac and that the system work with 300k as the low bandwidth is important to a smooth operating. I would like that you only bid if you have experience in this area. Only serious bidders please. I would like the first prototype in a couple weeks.