Xikers have their own tour, they finished the US last year and are just about to start their European leg. They did open for Ateez in the US last year when they were still kq Fellaz 2!
Xikers just like ateez were trained by bbt and according to the members they were at times provided additional support by yunho and wooyoung in dance. Xikers were the opening act for ateez world tour in 2022 which was hongjoong idea to get them accustomed to performing in front of a large crowd and they didgo to kcon before their debut but now these kids are going on their First world tour as Xikers, ATEEZ has their own world tour staring by the and of jan for 2024 As far as BBT is concerned they are not limited to KQ they have choreographed for a lot of other kpop acts. BBT does have a very good relationship with both ateez and xikers which you can seen by how they interact with ateez while on tour with them. there is a lot of camaraderie between BBT and ateez/xikers
Yes BBtrippin are their teachers, they also went to the US pre-debut (just like Ateez) to take classes there! Unfortunately with most idols they learn the basics and techniques pre-debut but after debut there simply isn't time to keep learning so all practices they do have to focus of learning or if they can't do it changing/fixing the choreo and preparing for performances. This lack of taking lessons just for the sake of improvement is most visible when it comes to singing a lot of senior idols (even from big companies) show very little improvement in their singing technique compared to their debut. Even Jongho from ateez said he only asked kq to get vocal lessons again during COVID (2 years after debut!) because he didn't have time to do it between the tours festivals TV appearances and comebacks.
That is unfortunate, especially on the dance side. But it shows the importance of still learning new skills within the choreographies given (Crazy Form for example) so I'm happy there is that!