1. I think some people prefer hiking to other kinds of travelling because they want to be closer to the nature. Sometimes the destination place can be reached only walking. But the main reason I see in money.
2. Because you have enough time. Travelling needs time.
3. Nowadays you can buy almost all the tickets you need through internet. But still you can go to a special ticket office of the railway company, or to the main station.
4. When I was about three, my parents took me to the Bulgarian seaside, and that was my first travel by air.
5. I think that today travelling by train sometimes turns out to be more expensive. If you book plane tickets very beforehand, they would be cheaper for sure. Also I think there are cases when you have to count not only the money, but your time as well.
6. I'm not sure, there is a big main station, and maybe 10 smaller stations. Если речь о Питере или Москве, ответ нужен другой - There are nine big main stations in Moscow; there are five big main stations in St.Petersburgh)
7. The main advantage is that you are the master of your travel, and you have your luggage in the trunk. Among the disadvantages are: the driver is never relaxing; it's dangerous and expensive to travel by car; when you travel for long distances you spend the days sitting.
8. During a journey by train people can look in the windows, sleep, read, talk to each other, play table games, eat.
9. Right now I do not have any special plans. Of course, I would like to go to the seaside or to the mountains, or maybe visit a beautiful European city, but by now I haven't thought about it seriously.