I'm on mini-pills.They are just as effective as regular pills. However, you have to take them more carefully. With a regular pill you have a few hours that you can take them within and they'll still be reliable. But yours need to be taken at the exact same time. If you're off by an hour, you need to consider yourself unprotected. That's why you found that the effectiveness was lower- because typical use rates are lower, because they're harder to use.
So if you take them at the exact same time like you're supposed to, you'll be fine. But just be really careful about it. With something like this it's useful to keep plan b around because sperm lives for a few days and the mini pill doesn't always stop ovulation. So, say you had sex one night and forgot the next day's pill- you might want to take plan b to make sure that if you ovulated the the egg can't implant. Know what I mean?
And no, there is no break for your period. You take the pills all the time. You might get your period at the regular time for you. Personally, I'm not getting my period at all anymore on the mini-pill. That is normal too.
But Eiri was right, always read your packet. I'm pretty sure all the info I gave was correct, but it never hurts to check! I wish doctors told everyone this information, it really is important. When I got my mini-pill my doc practically gave me a lecture on how to use it.
Hope that helped...