Keyword density: dead. Semantic matching has made repetition irrelevant.
LSI keywords: never were a real thing, but the concept has become real-ish — comprehensive coverage of related concepts now matters.
Word count: less important than answer quality. A 600-word direct answer often outranks a 3,000-word padded article.
Exact-match URLs: marginal benefit, not worth contorting URLs for.
No. Semantic matching has made it irrelevant. Stop counting; start writing answers.
As long as it needs to be to fully answer the question — usually 1,000-2,500 words for guides, 600-1,200 for focused answers. Length follows substance.
Not directly, but it affects CTR, which indirectly affects rankings. Write it like ad copy.
Sometimes. Mix exact, partial, and natural-language anchors. All exact-match looks artificial.