I think that cross platforms should really be emphasized (I would say it should be #1 or #2). Looking at the Ogre3D website, this is the first key competitive advantage that is highlighted. Even if Panda is not a mobile platform ‘native speaker’ yet (I do hope it will be become in the next releases), it is a true desktop multiplatforms engine. I think this should clearly be highlighted (with some notes/comments telling that next releases will include these capabilities).
In your item #3, I would probably illustrate “Powerful” by taking the advanced OpenGL / GLSL capabilities since 1.9 (e.g. compute shaders,…). We really should assure people that choosing P3D will not prevent them to unleash the full power of the graphics cards!
Yes - I think this is key. We should probably ask the community for a feedback on their mature projects (I remember at least one game that went to Steam - Signal Ops - [url]Signal Ops - A game that will multiply your perspective.] but there are hopefully other ones) and provide short insights that should be put in the front page.