How can i create custom vendor in BFA/Legion and how to fix an enemy ncp?

Hello again!

Firstly, thanks again for the help in day cycles, it works! :D

I would like to know how to create a custom vendor (vendor repairer, all mounts) in a BFA/Legion repack. I'm using HeidiSql.
Furthermore, i have a problem with some npcs. For example: I get combat with a gnoll and it doesn't attack, just follow me. If i hit him, he evades all my attacks. Also met this problem with some bosses. How can i fix this kind of bug?

Thank you for your help!

Best regards, Ensus :)