Yes, you can visit other continents and explore the land. Asking around Khal where the teleporter to Kojan is. Yes, some people will hate you, but it's very few.
Mordebi Human-racial hate list
Yes, you can correct your stance with them by killing their enemies. It's not trivial, but it looks like the entire Thestran continent is open to you. Just be careful when you approach a town.
Yes, you can travel and explore with your friend. The cat people are widely accepted, except on Qalia.
Kurashasa-racial hate list
Khal (Except for Foreign Quarter) (Khal can be gained via killing Ksaravi, Harami Bandits, etc.)
So get out there, young man, and explore. The teleporters will take you to different continents, and from there follow the roads to major civilization centers. Enjoy.