How old are you talking? In 02 they made a lot of really nice upgrades to the Explorer which included an independent rear suspension that make it much nicer to drive on the road. I think the 02-05 Explorer is pretty bland but I really like the changes they made to the 06+. If Carla would trade the Prius in on a new Explorer Eddie Bauer I'd do it in a heartbeat. I had a 97 Limited and the 95-01 truck is still that, a truck and it lacks refinement and safety when compared to the newer ones.
Oh no, the HIghlander will be more reliable and hold up better over time.
Oh its a much nicer vehicle, but the basic vehicle and many of the body panels are exactly the same. I'd say its 60-65% the same vehicle, where the RX is probably only 40% Highlander.