Standard questions

I’m completely new to this but love the concept and have some standard questions. Considering j2 that would be hybrid 2 days a week in office and my current j1 is fully remote. My meetings with my boss could be late night so technically meetings shouldn’t overlap ever. Some basic questions: 1. How do you handle updating or not updating LinkedIn? 2. I think my current job has something in the employee handbook about not having additional jobs outside of my current one or you have to check with management first. I’m assuming j2 will have the same thing. How do y’all avoid this conversation or you just don’t say anything to either employer? 3. Are taxes an issue? 4. What if I want to apply for j3 down the road, do you put both jobs on the resume / how do you handle background checks if so? Thanks for any answers/advice based on your experiences!