Customer accounts, forms, and questionnaires

Hi.

I apologise for the vagueness of this title, but I am hoping that someone here could point me in the right direction.

I have a need for a website that does 3 things:

1. Allows people to register an account with some basic information, but customised.
2. Allows people to make bookings/appointments and process payment information for these.
3. Allows me to create custom forms which brings in the information from someones profile.

So, as an example:

Mrs Bloggs registers with the site and gives her details.
She then wishes to make a booking, and does so.
When she makes the booking, she is presented with a form that asks her some questions. Her name, address, and all other details are already in the form.

Is this something that is massively difficult to do? Are there plugins for this, or do I need custom code?

Any advice would be much appreciated.