I would like to add a a feature to my site to collect user information

Ok im not sure what the name is for what im looking for. So ill do my best to explain what i need.

I am starting a business that requires thousands of people around the world to participate and complete small jobs here and there. This is not a Job Searching site or anything like that. Its alot more unique. So far i have around 18,000 people signed up, but the process on my end is almost completely manual.

This is what i am currently doing:
I have a wordpress website where users can fill out a forum which asks for their name, email, phone, country, city, and other questions. Once submitted, I get an email, with their info. I then open Excel and manually enter all the info. When i have a job offer I send it to all of the emails, and they reply if they wish to do the job. Each job has a different payout, and require different times to complete. This is a timely operation, and would like to automate the process.

I am wanting a website which users can go to, and register/apply to receive emails with specific job offers. I would like them to be able to accept or deny the job offer through the website, or email. I want them to log into their account and be able to see the jobs they have done, the money they have made, and other useful information.

On the back end, I would like to be able to see a list of all the registered users, and be able to filter by the city, country, age, sex, and more options. I would also like to have a section called Jobs which only I can see. Inside jobs, there will be Job A, Job B, Job C etc. When a user accepts Job A, and Job C, I would like them to automatically be placed in the Job A and C section. This way if a job requires 1000 people, I can see how many more people i need to accept the job.

Im sure there is alot of other useful options which would help also, but hopefully i explained it enough.

I was told this was possible using wordpress by a technician from a hosting company. If there is a better solution than wordpress, please feel free to post that also. Any information would be useful, from a complete solution, to even a word that i can google, and do my own research.

Thanks for taking the time to read this, and your helpful responses! ??