First  scenario.
Suppose there is a custom object, and we have 4 users. When a first record is created we have to assign the record to user1, second record to user2 and so on ...when the fifth record is created we have to assign to user1 again and iterative.
Second Scenario:
We have to assign the record when the user is available only just like omni channel...how can we implement this using apex. When i Say available it means the user is active in salesforce but he might be on leave not to accept records on that particular day...he might be away from desk which means he is not available to accept the record.
 

Is there any possibility of Integrating FOXPRO system with salesforce in Real time. I do not want to get the data in CSV files and update using Data loader. Any other Ideas, please post here.

As per the Documentation here, we cannot fire the Validation Rule after WFR's Update Action. Is there any way we can fire the Validation Rule after the WFR's field Update Action?