2. Most people in Russia do not speak English or do it poorly. Russian accent is very hard to hide even in writing. E.g. we don't have articles in our language, the whole concept of article is so foreign to us, that I, for example, just put them randomly, because even after years I can't understand why and where to use them. So it's easy to spot Russian comments.
3. There wasn't a single proof that Russia meddled in US elections, not even indirect evidence. It's mostly a bombardment of US media: "Russians did it" (and 100500 pages of gibberish without a single piece of evidence). Though there were no proofs, most people read only headlines and start to assume there was actual evidence. There wasn't any.
Also, I don't understand why would Russia support Trump. Any US politic hates Russia the same, be it democrat or republican. US is a fascist state waging fascist wars over resources (Vietnam, Iraq, Libya, Syria) that hates almost all the world because it considers itself a chosen nation and all the rest are savage nations. US inherently hates Russia. Always hated - read newspapers from 19th and early 20th century - the hatred was already there. Always will hate (just read comments under any news on Reddit /r/worldnews - many commenters say that Russia should be nuked, that Russians should be killed, etc).
Why would we care to elect Trump? Did he do anything good for Russia? No.
Actually, he appears to be a sane person unlike, e.g. Biden, so in our interest would be to elect a leader with dementia instead.