1) Aren't the policies just for a one year term?
Yes. Each year you have to renew.
2) What will the site be used for once we all have our policies chosen?
If people have a life change (like get married, job changes, etc.) you can get a new policy any time.
3) Is that site going to be used for a three month re-assignment exercise each year in ensuing years and idle the rest of the time?
No, see above.
4) Is that site just for this initial sign-up?
It's to sign up, and eventually renew, your plans. You can also use it to compare plans to make sure you continue to gt the most affordable plan.
5) Why aren't the Insurance Companies paying for a system that forces us all to opt into one of their pieces of paper?
Because it's a government mandate - we can't mandate the companies pay for it (even though we would probably have a working website if we did!)