Does the saltiness of water change by location?

Answer 1

Absolutely. Different parts of the Earth have really different salt contents. Take the dead sea for example, it has so much salt that nothing can survive in it. It also causes a weird effect which makes things float really well on it :p

Answer 2

Yes. Inland salt lakes are a lot saltier than the oceans. That's because the only way they can lose water is through evaporation. These lakes tend to be located in basins so there are no rivers flowing out of them.