Where to stress words?
I've been looking up a lot of words on Forvo and native speakers seem to stress some words in different places than does the "robot" generated voice. Is there a rule as to where to place the stress?
No, there are no general rules for knowing where to place the stress, you have to remember it for each word (and there are even words written the same way that mean different things depending on the stress).
Actually, stress in Russian is very important and changes how you pronounce many vowels.
Unfortunately, they couldn't show the stress in the course for technical reasons (excepting in flash cards). More info on that here : https://www.duolingo.com/comment/11461522