User Activity

I was wondering if I may use my phone as a hotspot for my kids to connect their tablet or phone when we are on long road trips. would this be posible or am I not allowed to do this?
for the past week and a half I have received a few callbacks from people I do not know, I have not called them.... I also get random missed calls, and when I call back, the person states he/she has never called my number.... any one experiencing some...