How to create custom text boxes in themes for user info storage

I am currently in the early design phase of creating an online business. I already have the template picked out. The functionality I am unsure of how to integrate is this: I need to be able to have the customers create a user account and store information with custom fields that I designate.
1. What is the technical name for these fields?
2. How do I create the back-end so users can create accounts that are password protected?
2. How do I integrate the user data fields into the front-end(the template)?
3. How are these fields connected to the back-end?
4. Am I looking too deep into this?
5. Should I be looking at a different solution?

I’m very technically savvy(I’m the guy my friends and family call to troubleshoot their computers), but I’m no coder. I already have a tad bit of design and coding experience with my own personal blog, but on a very basic level.

Thanks,

Craig