Which court is a possibility if$...$

Sully is from Texas and Mike from Alaska?

Original facts, Sully wins a $$1$ M judgment, but Mike contends there is a harmful error of law?

Sully and Mike are Texans, and Sully sues for $$50,000$ for negligence related to ocean transportation $($maritime$)?$

Sully is from Texas and Mike from Alaska, but the contract is for $$50,000?$

Same as above, except the cause of action arises from a federal environmental statute?

If federal court jurisdiction is allowed, can parties choose a federal court in any state?