How quick your animations should start playing depends on how you handle the triggers in your character blueprint.
Locomotions aren’t divided into two being IK supported and not supported ones. You just add control rigs on top of the animations that are currently playing.
This doesn’t have anything to do with locomotions either, the smoothness between animations can be adjusted to your liking. By smooth movements, if you mean motion matching animations, you can check out the Game Animation Sample Project which you can download for free via Epic Launcher!
Now, there are many great tutorials out there that you can find online, but I think this one right here is the simplest one:
If you don’t have an animation blueprint yet, you can watch the previous video in the series which is the #9
You can handle different locomotions like ground movement, air movement, etc. by creating seperate state machines for them.
Hope this helps! 