1) Ours would last the whole trip. I'd test it before you go. Have it run for as long as it will last.
2) I always pack granola bars, rasins and other snacks in my check luggage for the hotel. I'd try to make a grocery run if you are going to be there for a while. That said, eating healthy while traveling can be a challenge.
3) It would depend on the offer/person. I'd REALLY want to know about the carseat. We have always traveled with both stroller and car seat. I'd borrow a carseat from my sister or a good friend who I know is like me when it comes to car seat care/expiration dates etc. but my kids might perfer their own. We've never borrowed. I'd borrow a stroller
/hillary
DS #1 Summer 05
DS #2 Summer 07