<span>Vladimir Lenin became the head of the Russian government after the October </span><span>Revolution of 1917. </span>
Pretty sure the first one
He disrupted their way of life. Many natives were killed, because they felt threatened by their existence.
<span>It expresses more complete ideas.</span>
A non-restrictive modifier add information that does not restrict who the subject can refer to (compare to "The one Marlena that enjoys many subjects" -this one restricts the subject to a specific Marlena). Here it's "who enjoys many different subjects" - it adds additional information about her, but doesn't change the referent.
