How to Choose right plugins and theme for the following wordpress site

I want to seek help in creating a website through wordpress. I read somewhere that most of the task that we can think of are already present in the form a plugin in wordpress. Hence I want to know what plugins could be helpfull for me this task. Below are my requirements:

I am designing a website, where I would like to sell services (which could be anything like training, or advice, or consultation) at a fixed price say X amount. I would like to have both consumer (as consumers) and service provider (as workers or providers) registered on my website.

The consumer should be able to login to their account and can purchase a service by paying X amount and can provide the date and time on which they want to receive that service.

A service provider will login to their account and they should be able to see what all services are requested and available to work on. They should see all the pending service request ready to be picked upon

Then they can pick the service request based on their skills and should claim that service request so that no other provider can pick it up. Once a service provider claim for a service request the consumer gets notified by a message that you request has been approves and will be serviced by us providing the time of servicing.

After the provider is done with completing the service, the service provider gets amount 90% of X in their account, which they can withdraw at any time. 10% of X is taken as website charges.

NOTE: similar functionality I have seen in few sites like transtutor.com, and assignment competion sites as well.

Thanks, Sourabh

via Chebli Mohamed