رضا: This kind of question can be most easily answered by the native speakers. I would say that:
Trip is interchangeable with journey, voyage is a journey to some very distant place taking lots of time, travel is the act of travelling - it's more general term encompassing the other four, and excursion is a short journey.

رضا: The English verb 'visit' is derived from the Middle English visiten, ev. from Old French visiter, from Latin visitare, frequentative of visere, which means to want to see, go to see, from videre, to see.

Hrqls: Heh, if I were like you, I would be constantly yelling when watching TV or reading newspapers.
I remember a situation when there was this sentence written on TV: "Mají doma krokodýli" (There should be 'y' at the end). After a minute or two, I guess after a phone call from some viewer, they changed it to "Mají doma krokodíli". LOL Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

Hrqls: That's an interesting point about the articles. In Czech, there are no special words for them, but they are formed as suffixes and their usage is more complex. I often have the same feeling that in the future, we'll have only one gender, just like the English, as people keep mixing and mixing them. :)

How 'bout 'pions'? :) Is that "ugly too? LOL

Hrqls: Right. That's how it works in all languages with multiple letters for the same sounds. Reza would probably be able to tell whole stories about all those 'Z's and 'S's in Farsi. :)
Fencer: The Czech "translation" is perfect, of course. As far as I can tell, however...:) Plus note that I said "almost".

Hrqls: I bet the Dutch 'g' and 'ch' can be quite tricky, huh? Same thing with the Czech 'i' vs. 'y' and 's' vs. 'z'. It seems to be almost impossible to find a Czech who would speak and especially write proper Czech. :)

Asking a native speaker is the worst thing you can do if you want to get precise information on the grammar of any language (unless such a person is a linguist, of course). Native speakers take their language as something "natural", they don't really think about the construction and linguistic meaning of their sentences. This MUST and HAVE TO thing is a good example of that. The difference between these has absolutely nothing to do with importance of what is to be done, as SR suggested, although it might actually seem so in lots of cases. The "truth" is as follows:

There are two fundamental meanings of MUST and HAVE TO - the first is used in cases when the speaker wants to express a necessity or obligation to do something. Now if it's an obligation or necessity caused by external circumstances (e.g. provision of law, prior promise, a need to get some information, the situation itself, etc), we have to use HAVE TO. It's also useful to remember that questions with MUST aim for wishes or intentions of the person asked.
Compare these sentences and think about if the MUST could be replaced with HAVE TO or vice versa:
Some day I must ask him why he did it.
I'm sorry, but I must insist on an answer.
You can go there, but you must be home by six.
Walter's the expert. We'll have to ask him how it works.
I have to laugh when I think about it now.
Must you leave so early? --- I'm afraid I have to.

The second meaning is used when we are sure of something, since it can be logically derived from a particular situation. Here, we have to use MUST.
What a marvellous offer, he must be very generous.
You must be crazy to want to marry her!
I always know what I want. --- That must be nice.
Romantic music must have shocked its first listeners.