2. The 3.03 loads 9 seconds even with an empty scene. Isn't it loo long?
This is normal for the first render each time you start Modo - since the plugin needs to authenticate Octane.
3. When I open modo (empty scene) and go to Octane Render tab and then 'Octane Kernel' and try to drag the first available 'Octane/Modo Render Camera' channel Octane crashes.
I will look into this. Someone indicated this was a bug in an older version of Modo. Which Modo version are you using pls?
EDIT: It is crashing for me if I drag the Render Camera from the Render item in the Shader Tree - so this is a crash in Modo unrelated to the plugin. I suggest you report it to TheFoundry.
I added another camera but when I choose it from the camera modo list the viewport does not change.
You need to change the /Render/ Camera - which you can do via the Kernel panel, or the Render Camera property of the Render item in the Shader Tree.
Paul