For issues you find with the Switch and Console releases, please follow this link and give as much detail as possible. This is the speediest way to get info to Pipeworks and get a hotfix in the works.
For issues you find with the Mobile 1.3 update, please follow this link and give as much detail as possible. This is the speediest way to get info to DR Studios to look at your issue. Also, some troubleshooting hints here.
Technically 2d but it is sorta a 2.5, think of it like smashing a glass panel straight through our world and smashing another in to restrict you to a 2d-ish plane. In other words, you are in a 3d world in a way, but you're heavily restricted via both game mechanics and how it would be messed up if Terraria was 3d. Another way to theorize is that you're some sort of omniscient watcher or whatever and are looking at the world in the way a guy looks at an ant farm.