Long trip issues for Newbie

I find stopping every 2 hours or every 100 miles takes care of the bladder problem before it becomes an accident. Also stretch the legs and you will feel refreshed for the next leg of your journey. One of those stops can be a fuel or meal stop. 300 miles a day give or take 25 miles, is plenty in my opinion as long as I have called ahead and reserved a spot to camp for the night.
You will know when the wind gets to high then plan on stopping until it abates.
Your engine computer should take care of any changes in altitude. Just don't be afraid to downshift going downhill to save your brakes.