Procedure for creating log in functionality with admin?

Looking through all the extensions is confusing me with how to get a working log-in system going with some extras tailored to my site. Where do I start?

I need registration, log-in area, profile (with address, billing, shipping, etc), and a few extras:

Quotes pending (submitted but not yet reviewed)
Quotes in Progress (reviewed and quoted)
Quotes Completed (completed)

So this is going to be for my embroidery business in which someone is going to be able to review all the information on the site, register, get a confirmation email, then have access to a profile area where information will be updated (name, address, phone, etc). There will be an area called quotes where the customer can enter through their account and click submit a quote. Information will be entered by the customer and they have to include an image to be quoted. Then it falls into their "Quotes Pending".

This is where the admin area comes in. All the quotes get sent to my account "quotes pending" where I get new options for customized message and price back to the customer who sent the original quote. When I do this, it goes into their "Quotes in Progress". They can review the information and if it seems correct, they can choose Payment for Quote, in which they pay the price I quoted them. It goes into their "quotes completed", and my "quotes in progress". When I finish it, I click quote completed and it moves it into my "quotes completed"

So there would also have to be a past orders area where they can download their file again if needed, and a "rate our service" (testimonial) area.

So there is a lot going on and I am confused on where to start. What should I do first? Hopefully we can keep this thread active and when I finish a step, we move on to a new one. No need to give detailed instructions, just be helpful with something like "create a website with a template and 3 editable regions, then use security assist to make a registration form." etc etc, General steps can be given, and I will figure out the nitty gritty stuff.

Thanks a bunch!