How much power and autonomy should Texas have in relation to the federal government? Why?
This is an essay question. No one can write it for you. The United States Constitution spells out the powers delegated to the federal government and the relationship to the states. Amendments clarify those distinctions, specifically stating that the laws of the United States apply in each state. I recommend you read the document. This website may help you understand it.
http://www.nga.org/cms/home/federal-relations/nga-policy-positions/page-ec-policies/col2-content/main-content-list/principles-for-state-federal-rel.html
Here's another point of view:
http://www.ushistory.org/gov/3c.asp