I don't think you will have any problem with them. But, like any other fish that you put in with your betta, just keep an eye on them for a little while to be sure.
Kuhlis are mostly bottom dwelling fish and will have no conflict with the betta over territory. They're a lot of fun too, especially when kept in a group of 3 or more.
They should do alright with the kulhi loach, I have 2 with a couple of females and a male and they are all okay. The kulhis just go abouts to do their daily busniness and dont bother no one. Such nice fellas.
But bettas are known to be different from each other in personallity wise. But even so they should be just fine
My betta is in a tank with a kuhli loach at the moment and, they haven't noticed eachother in the past 3 days [when i added the loach] My dad also told me that loaches taste bad or something like that. One of his african cichlid tried to eat one but quickly spit it out in disgust. It lived too.