Exchange 2003 and exchange 2010 SP2 coexist

Hi,

I have installed a new Exchange 2010 SP2 server in our environment so its coexist with our old Exchange 2003 server. Now I need to reinstall the exchange 2010 SP2 server to SP1 version because a few applications doesn't work with SP2.

I haven't moved any mailboxes/distributionlist/users to the new exchange yet.

My questions

1: Which is the best way to perfom this downgrade(reinstall of ex2010) and make it works again as a coexist machine?

2: Can I save configuration for organization config and Server config?

Thanks for your help