To be more exact, плывёт means motion in one direction, which mostly gets useful for actions in progress.
Плавает means motion in more than one direction. It may be used for:
- repeated, habitual motion (these usually imply that you come back, then start it all over again)
- round trips, especially when "I went to the park (and returned)" is close in meaning to "I was in the park"
- motion without a goal. This can be progressive or habitual.
- the name of the action itself: the ability to perform such action. For example, if someone cannot swim, it os «не умеет плавать».
Other verbs of motion behave like this, too. One verb for one-way motion, another for multidirectional motion.
I get that е in не is not stressed, as the whole word is not stressed and therefore it is pronounced like the i in lid. But I was taught that in a one syllable verb the vowel is automatically stressed. Is that then simply not true? or is it like a rule as LucianoArthur suggested that both can't be stressed because the two е clash?
thank you in advance for the help!
Some words tend not to be stressed, among them prepositions and particles like не, ни, же, то, ведь, ли.
There are some preposition-noun combinations where the stress moves from the noun to the preposition (Он упал на́ пол) —some of these are historical, some are coined by analogy with historical stress patterns. The particle не gets stress in не́ был, не́ было, не́ были (but not не была́)
It might depend on a person. I personally do not use кушать in generalised, non-human or non-familiar contexts—so, essentially, I would only ever use it to refer to someone I know having a particular meal. Some people, on the contrary, do not find sentences like "Я не кушаю мясо" or "Медведь может скушать собаку" odd. For me it would be «Виктор вегетарианец. Он не ест мясо.»
Note, however, that кушать is generally a much less common verb than есть. In the spoken subcorpus of Russian National Corpus forms of есть are 10 times as common as forms of кушать, with imperatives (e.g., "Кушай, конечно") being a bit less unfair but still in favour of есть. Ironically, it is old literature where you find it in buckets.
The corpus information is interesting because here in Kazakhstan I have never heard est' in the imperative and rarely hear it in any other form. I hear kushet many times almost every day. Could this be a difference between Russia and Kazakhstan, or is it just the circles I travel in?