What plug ins would I need?

I am planning to build a site and am not sure which plug ins I would need, or even what they would be called so I can search for them.

If anyone can give me a heads up I would appreciate it.

The easiest way for me to relate which plug ins I need is to give you an idea of what I want the site to do. I have thought of an analogy for this.

It is of course hypothetical.

The website is a scout “buck a job” site.

Each scout group signs up and registers the name of each scout in their group under their own account.

When a scout completes a “buck a job”, like mowing someones lawn or something, the person who has had the job done for them visits the website and puts the scouts name and what they have done into a form.

The form data is routed to the specific scout group that has that name registered and a report shows up in their client area and an email is sent to the scout leader to notify them it is there.

Thats one part of the website.

The other part is the quiz part where each individual scout group can set up a quiz for badges etc and give individual scouts their own link to their own quiz. The results are posted back to the scout leader.

Pretty much thats it. I am not certain how to tie it all together.

It needs to be able to handle thousands of scout packs though and their could be hundreds of scouts registered in each group.

I am not fussed if I have to pay for the plug ins – they dont have to be free ones.