Expressing ‘want’, ‘need’, ‘must’ and ‘have to’

How to say “I want to swim” (Expressing “to want” with Infinitive + the verb istemek)
How to say “I need a taxi” (Expressing need with dative + “ihtiyaҫ”)
How to say “I have to go” (Expressing need/must with “lazim” and “gerek”)
Expressing need/must with the verb “gerekmek”