@MurMur: My point is that all languages have features that seem unnecessary to outsiders, but to natives are valuble, because they have a practical use or add a "poetic" quality to the language. That's why I mentioned the definite vs. indefinite adjective in Slavic languages ("novyj", "novaja", "novoe" vs. "nov", "nova", "novo" in Russian), because while this distinction has a stylistic value in Russian, and still retains a practical value in Croatian (in Croatian "visok chovjek" which means "tall man" vs. "visoki chovjek" meaning "a man distinguished by tallness among other people"), to an English native this distinction may seem impractical.
It's the same situation when a Russian like yourself thinks about English articles. To an English native it is important to be able to distinguish a particular object among objects of the same kind. That's why Littlefoot says "not a lone dinosaur, the lone dinosaur" to emphasize the significance of this particular lone dinosaur. In Russian this significance would have to be expressed in a different way, like "only lone dinosaur" or "lone dinosaur my grandpa talked about". The English language could work without articles, but in some situations you would need more words to express the same thing, and the language would lose some of its distinctiveness, some of its "beauty".
Regarding the difference between the tenses, the Past Simple expresses an action of short duration or a habitual action ("the sun shined") in an undefined past, while the Present Perfect express an action that ended recently ("the sun has shined"). When using the Past Simple there is a sense of distance between the events of the past and current events, while with Present Perfect the past events still feel immediate to the current events.
As you can see, English has more complex system of tenses than Russian.
As for English always needing more words to express the same thing as Russian, this is not always true. How many Russian words would you need to translate "quarterback", "fog of war", "raytracing", "hard-wired", "finger food" or "antiestablishmentarianism" to have exactly the same meaning in Russian? Also, keep in mind that English words even when they are more numerous than Russian words in a text, the Russian words are usually longer and take longer to pronounce (that's why all languages, per Noam Chomsky at least, carry the same amount of information per syllable).
Speaking about complexity, I already mentioned that English matches the morphological complexity of Russian with its tense system, its syntactical complexity and its ability to form new words and idioms. In computer science, for example, how many technical terms have been borrowed into Russian from English, versus how many of them have been successfuly translated into Russian?
And I thank you for offering help with Russian. I hope you won't mind if I start bugging you with helping with scientific articles and such

. I make many spelling errors in Russian because I frequently mix up words with Croatian words, because Croatian is closely related to Russian (close enough to interfere, but not so closely that a Russian and a Croat would be able to understand each other without tremendous effort on both sides). It can be solved with more dilligence and a good Russian dictionary (which I don't have, unfortunately, but I will work on getting one).
And yes, I as well would like if a mod could separate this discussion in a different thread.