Making a membership dating plugin

Hello Support guys:

I want your help and advice in pointing me in the right direction for a project for a client.

The client wants a dating website, but catered toward a very specific demographic.

The website should allow user to :

1. View profiles of other users, which will have images of the users, and details (their age, height, hair colour etc) as well as some text about them.

2. Users should be able to message each other (not an IM, but rather good old fashioned messaging.)

3. When they sign up, the users will be asked quesitons (the answers to which will appear on their profile page) - e.g. do you have kids? Do you play football? etc

I hope you can help by pointing me in the right direction... i understand this may require custom coding - which is fine, i will be getting some people on board for this, however i wanted to know what i should be looking at first in terms of how it will work etc.