How do multisites work?

Hello again Dear Volunteers,

I’ve read what help files I could find on multi-sites, but haven’t found any that relates to my questions, so I’ll give a shot at posting it here.

I work for a yacht club and would like to change our entire website over to WordPress. We also host international races formed by committees and those websites traditionally have been stand-alone websites. The races have very different brands from our club, and the committees like to keep their own presence.

This is fine, but we also need them to be associated with the club, so we are trying to figure out a way to host both sites together, with separate brands, but with a way to merge them completely (under our club brand) after the races are over. This would kind of be like turning them into a sub-section of our website after the fact.

1. My first question is how can we do this? Is it possible?

The needs for the races (and us too) are:

Online registration
Online payment

Here is a quote from the committee asking for my help:

In my thinking on all this one quickly comes to the conclusion the template needs to start with the website at the club. I have developed for the two regattas I have chaired from scratch websites independent of the club website. This is inefficient. I have a template through Dean at Colour for the Youths and we are in the process of revamping for the IFDS event. We need a website at the club that can be adapted to any regatta we plan to host. This includes , online registration , online payment of regatta fees , NOR;s SIs , You tube clips , press releases , sponsor stuff. Eventfully we need to approach the Marblehead this way as well. Right now when I go to the club site one would think one of the biggest ocean races in the east is not even associated with the RNSYS ! Why would anybody want to be a sponsor of this race.

2. My second question is, can WordPress seamlessly incorporate online registrations and payments?