In fact your third example could be modified to the hypothetical 'If you learnt (or were to learn) Spanish, you'd (you would) get a good job: Si aprendieses (aprendieras) el español, consiguerías un buen puesto

Hi I hope my muddled, but 20 year understanding of the subjunctive helps; 1: you never use 'Si' with the present tense subjunctive. This type of conditional is usually followed by the imperfect subjunctive. This is the English equivalent of the second conditional. For example: ' If I had time, I would read more: Si tuviese tiempo, leería más' 2: the subjunctive is used when there is a change of subject separated by 'que':, usually involving desire, order or wish 'I want them to learn' - 'Quiero que aprendan' 'Tell him to call me' -'Dile que me llame' 'It's important that they listen' - 'Es importante que eschechen' 3. In my experience, most first conditionals are usually reduced to simple present tense: 'If it's a nice day on Saturday, we'll go to the beach' - 'Si hace buen tiempo el sábado, vamos a la playa'

Sorry - I did post a correction, but for some reason it did not send. I'll try again later when I'm at my desk :-)

University students should study whatever they like, or only  useful subjects

Nowadays a significant majority of students complain that they don't know what they should study at university. Their teachers and parents usually suggest that they study some useful subject which will help them to find a good job in the future, whether they like the subject or not. They are forced to study for the purpose of working. In recent years, in job markets there has been a high demand for Science, Technology and Economy,  and in correspondence, these have also became the most popular subjects, moreover, those who want to be more competitive, will also acquire more skills. This phenomenon benefits employers, they will always find highly specialized employees, for those who desire to have a good job(, might also not stop improving themself.) (??)
Everyone wants to have a good life, however, not everyone is so pragmatic, there are some students who want to study whatever they like, maybe they are not fond of Science,Technology or Economy, (in contract, ??) maybe they are keen on History, Lecture or other subjects which may not seem to be useful. They don't have any specific aims, a good job or payment, maybe they only want to resolve a difficult mathematical problem or write a beautiful poem. I really admire those who know what is their interest, studying should also be a resource of pleasure,additionally, as we say, interest is the best teacher, learning a specialized subject requires a heavy personal investment in term of time, energy, to reach a competent level, a high degree of motivation is required and this can usually only be maintained if there is a strong personal incentive. They usually feel more satisfied and happier, since they never have been forced to study.
In my opinion, students should study whatever they like. A happy life is more important than a good job and moreover I don't think that there exists such a thing as a useless subject, in this multi-cultural world, every subject has its own value. In addition, almost all successful people tell us that the most relevant reason for their success is  passion. Needless to say that those who study for their interest are easier to be successful.(may find success easier?)

What did you want to be as a child?

When I was a child I dreamt of becoming a ballet dancer. But that wasn't going to happen, because I lived in a small town and there wasn't a ballet school. But I watched (any/ every ballet performance) and then I tried to repeat all of the pirouettes. I wanted to look at dancers for hours (I wanted to watch dancers performing for hours). In my country it's possible, because ballet is very popular and it's frequently broadcasted on TV. Until one day when I rather foolishly twisted my ankle. My career as a ballet dancer ended, but sometimes I like to remember - `( think about it.) Anyway, I really can dance...