Is it "bad" to want a "materialistic" happiness? After reading several articles and a book about Buddhism, I now feel a bit uncertain about what Buddhism actually is about. Am I not allowed to dance? To sing? To fall in love? Is the purpose of Buddhism to become a munk or nun? To meditate and never get a taste of life?

Is it "bad" to want to travel? Is it "bad" to want to be happy and/or content?

Is Buddhism about finding happiness in Nirvana? Is that really it? Is it not about being happy where we currently are? Are we not allowed to truly live in the moment? 

I am quite new to everything about Buddhism, and I apologize if anything I've said in this question is insulting or rude. I don't know who else I can ask questions like these. I hope someone can explain to me.
The question is not one of being "allowed" or "not allowed" things, you're taking this too much like a dogmatic religion. Buddhism is more like a form of psychotherapy that comes with its own philosophy that it needs you to understand for the method to work.

The therapeutic method comes in an if-then formulation: IF you do this, THEN that will follow; IF you don't want that to follow, THEN don't do this. Its focus is suffering and the thing it teaches you how to do is eliminate a necessary cause of suffering that is present in your own psyche and without which the suffering cannot happen. If you don't feel any suffering or don't want to eliminate it, then there's nothing to do, you can ignore the Buddhist method. If you do feel suffering, you have in Buddhism a most efficacious method of eliminating it, namely by stripping away one of its necessary causes.

The necessary cause of suffering that's contributed by your psyche is having expectations. An expectation is a certain insistence or dogmatic belief that things having to do with your life must be or remain in a specific way (this is what they call "attachment" - this insistent belief or strong expectation). Unavoidably whenever you entertain such an insistent belief you are setting yourself up for disappointment and suffering - "things must be or remain in this exact way or else... &lt;insert negativity&gt;" - and life, being a process of continuous change, will be all too happy to provide these violations to your expectations and produce said suffering. So to the extent to which you want to avoid suffering, to that extent you must abandon your insistent belief that the world "must" be or remain in a certain way, e.g. that you "must" keep your current level of wealth and never go lower, that everyone in your family "must" remain alive and healthy forever, that you "must" keep all your limbs forever, that you "must" benefit from your current good relationships forever etc. etc. Any of these expectations can be violated by the process of life at any time, and this will immediately cause you great suffering because of your insistent belief that these things must stay constant, especially for you, forever. But the process of the universe is not tuned to such static(!) wishes, and the sooner you understand this the more immune to suffering you will be.

So the short answer would be: sure, enjoy every kind of sense-pleasure and emotion and feeling and whatever you want to enjoy in life, BUT... if to the pleasure you also add an insistent belief (expectation, attachment) that the pleasure "must" last or stay with you for X amount of time, know that you are setting yourself up for disappointment and suffering. If you want to avoid the suffering part, just feel the pleasure that is there to be felt in the present moment and don't create any beliefs about how it should behave in the future. If it continues into the next moment, that's fine, and if it ends and is replaced by some pain in the next moment, that's fine too, because pain is also something that arises and then ceases, and doesn't last forever. Learn not to cling to things, be they pleasant or unpleasant: this is the essence of the Buddhist teaching.