Create a customer accounts section

Hey,

we’d like to create a section on our wordpress site that would:
1. allow clients to log in
2. store details about how much work they have done for us
3. store details about how much money we owe them for that work
4. allow them to request money
5. allow us to email them

Is there a plugin that can do this?

Am not a programmer. Do not know what a plugin is. Sorry if I worded this wrong.

Thanks!