Query data base every minute and pass the JobID to a Service that will take more then 30 mins to execute.Shall i use duplex binding

Question

I will explain in steps excatly what I want to my application to do
Step1:-Query data base every minute and my data base table will contain time.If that minute matches the time. Return the JobID
Step2:- Once you get the jobID pass that JobID to WCF service and that will execute certain steps to insert data into data base.

Question 1:-Shall I simple create windows service and using a timer to periodically check the updated data.And pass the job ID to WCF service.

Question 1:-Shall I simple create WCF Client and service where Client will be quering the data base and return the result to WCF Service. Shall I use duplex binding.

Once the jobID is passed to any service to process it will take more then 30 mins. And there will be more then one job running at the same time.
Any help  is most welcome