How to deploy applications in sap portal 7.3 and access that application in sap portal 7.0

Hi All,

I have a requirement where in i have  my production CE Producer  portal is in 7.0 and current applications deployement are happening in 7.3.

We have a external supplier portal which will be in 7.0.

My questions are:

1) How do we access the applications which is deployed in 7.3 portal to 7.0

2) How do we do the SSO between the 7.3 and 7.0 portal

3) Do we need to  create a system object in external supplier portal which is in 7.0 How can i do that??)

4) would the accesibiltiy from ES portal be done throught remove iview assignment and if yes how could i do that ??

Could you please help me with this?

Thanks