1 - There are a lot of variables on timing. The synch from CRM into Eloqua is configurable buy the client. 30 minutes is the most frequent it can be run
2 - Each CRM environment has it's own limit based on the complexity of the set up and processes that are running
3 - SSO is available for Sales Tools (profiler and engage), but not switching back and forth from Sales Cloud to Eloqua
4 - It is recommended to manually upload the records initially from Sales Cloud into Eloqua