Because the Buddha's true teachings are to always go inside oneself and examine one's mind, the advice you will get is intended to inspire you and make you reflect on the nature and value of your question.

The advice given here differs from simple fortune telling, because it will put your Higher Self at work and you will find your own answers to your spiritual quest. For that purpose, your question should not be one that requires a straight "yes" or "no" answer, but one seeking advice.
For example, instead of asking "Will I marry John Doe?", you can ask "Where do I stand in my relationship with John Doe?".

Why would the answer I get be the one meant for me?
Because of synchronicity... please read below!

Even when an answer doesn't seem to apply, if you were really focused on the question and picked the image that attracted you the most, that is the specific advice meant for you.

Try to meditate on it and you will find that somehow it will bring hidden issues to your attention.
Maybe your relationship with John Doe in the grand scheme of things is irrelevant and there is better yet to come!

What is Synchronicity?
All divination systems are based on the principle of synchronicity.
"Synchronos" is an ancient greek word that means "[happening] at the same time".

When two events seem to unfold simultaneously for no apparent reason, it is never by chance. There is always a reason why amongst the randomly infinite possibilities and combinations, that one particular event manifests, rather than another one.

Synchronicity happens all the time, whether we notice it or not, and it is part of the workings of life.
What makes it a valuable tool for growth and learning is the aware mind that notices it and reads through the lines. The Universe often speaks to us that way...

One example is when someone goes to the nearest grocery store to buy milk, only to run "by chance" into an old friend or a stranger that tells us about a particular class or event, which we end up signing up for or attending, and that will turn out to be a life-changing experience.

Most often, synchronicity happens without our interference, but sometimes we can consciously "induce" it, like in the case of divinations, and learn from the message we are given.

Why are there 22 advices?
Because this Oracle is inspired from the Major Arcana of the Tarot, a very old system of divination.
In the Tarot there are 22 different Arcana, describing all the archetipal energy patterns of the physical and spiritual world. They represent the way in which the Universe and all things created come to expression, manifest and evolve.

How often can I ask the Oracle?
Ultimately, it's up to you. Please keep in mind though, that when we ask the Universe, we should do it in a respectful manner, in order to get a meaningful answer. And that includes the frequency with which we seek for advice. If we ask the same question three times within one hour, we have definitely overdone!
Once daily for general inspiration seems to be appropriate.

Enjoy the Oracle and may the wisdom of the Buddha enlighten your days!