1) The document discusses the different ways to express future tense in English using will and going to.
2) Will is used to express decisions, predictions based on present evidence, and promises or offers. Going to is used to express future plans and intentions, as well as predictions based on present evidence.
3) Other ways to express future include using the simple present or present progressive tense with time expressions like "tomorrow" or "next week." The future progressive and future perfect tenses are also discussed.