One more question...can I take my boat out there and just use the trolling motor since I have more than a 25 horsepower motor?

Yes

Would it be worth a 90 mile one way trip to fish this lake tomorrow 9-29-18. Anything biting. Would be fishing off a boat.

Yes. As long as you don't run the outboard.

Yes you can use your motor to load and unload your boat and you can use your trolling motor. And if required some areas will let you use your motor for the charging of your battery for trolling.

Yes you can