Axle questions

Hey guys I’m wondering about the term “floating axle” whats so bad about it?
Is it better to have a long axle or a short axle for what reasons?
What is retapping?
I really dont know about these things about axle but can you help me?

Floating axel means the axel has space even when screwed in
Retapping is when you repair the threads to fit a new axel

Long= less striping short= more striping (correct me on this one guys)

Also for future reference make sure you post in the correct place ie mods and modification or help/recommendation