Hi, here are my quick replies to your questions:
1) Create the reaction as you normally do in the SimBiology desktop and then enter as reaction, choose as kinetic law "Unknown" and enter the kinetics in "ReactionRate". This way you can use any kind of Reaction rate you can imagine.
2) Click on the small, downwards facing triangle next to the Navigation bar and select "Export Model to Workspace"
4) I am sorry, but I don't understand your question. Can you please explain this a bit more in detail?
I hope this helps.