I am trying to understand how this will be a currency.
I don't understand the point of asking that question that question. Like any other currency it's utility lies in being able to exchange it for goods and services.
The fact that it pays interest is not going to create a situation where everyone hoards and never spends. I would surmise the opposite would happen, why not spend some if you will earn it right back in interest?
People don't need much encouragement to spend money so your line of inquiry is based on a misconceived notion that the inclusion of paid interest will create a situation where no one ever spends their currency.
Do you ever spend your money? Do you ever cash in a CD and spend it? Do you ever liquidate your money market account and spend it?
This is a useless question imho.
Yes I do spend my money. I am trying to decide right now if I want to spend some more of it on Mintcoin.
I do not earn money off of interest currently. In fact I pay a lot of interest to others. I would definitely think twice about spending my money if I know I can get 20% interest on it by keeping it and doing nothing. Especially if I already have another currency that has a lower interest rate return that I can spend instead. That is basic investing principles. Borrow money for less interest (cost) than you can make by using the money for something else (profit).
I think it is safe to assume that everyone in here has some of this coin (myself included). Why do you think any large amount of people would suddenly decide to give us control of the vast majority of the money supply? Just because we were first? They might do it because we promise them a 20% return on their money every year but that is going to lead to inflation so the money might not be worth the same at the end of the year. Maybe we could give them something unique in the currency that they can't get somewhere else. Are we doing that here?
OK time to dump ;] 
