I will answer you with examples in English: does the vowels in English help us reading? Probably yes, but one still should distinguish between the "oo" of "look" and of "door", and between the o of "more" and of "move".. In the same way, letters like א ה ו י supply us some hints according to their place in the word, but it is far away from 100% guarantee.. So in order to be fair, the vowels in English are doing 90% of the job; while the letters אהוי are doing just 50% of it..

Yes. But only in general :)

Thanks, D-R! :)

In addition to Gery's comment, there is more things that help us in correct reading, like structure of the word and other but still it is only in general. I prefere to teach most of them only for advanced learners, because in the beggining it only prevents. Good luck with your Hebrew, Jesse!