Travelling with 1-year-old

My SO is releasing from the military next month after a 12-year career, so before he starts his new job in February we decided to take a family trip to Disney World! We’ll be flying from Canada with my 9-year-old and my son will be 13 months by then. He’ll be on our lap during the 2-hour flight, so we’re not planning on bringing a car seat, then we’ll shuttle to the resort we’re staying at.

My question is to those who’ve done a similar trip, if we want to rent a car to drive somewhere, do car rentals typically also rent car seats? We’d really love to make the drive to the coast so my kids can see the ocean for the first time. Also, if we brought our stroller, how would we transport that? Do they allow that on the plane like they sometimes put luggage up front or would we have to check it with our luggage? (Sorry it that’s a dumb question lol) Our stroller folds pretty compact but the seat has to come off to fold it, so I’m thinking maybe purchasing an inexpensive umbrella stroller might be worth it. First time travelling with my kids by plane so no idea what to expect 🙈 thanks!