"I have" and "I've got" both mean possession. Also, "I have to" and "I've got to" both mean obligation.
When we use "got", it's always with a contraction: "I've got". "I - have - got..." is not natural. In questions and negatives, we use "Have you got...?" and "I haven't got..."
"Have" can be a main verb or a helping verb. The helping verb functions differently, compared to a main verb.