1)  Let's say a cousin of mine is planning to come to my graduation ceremony on a tourist visa. If that cousin decides to permanently stay in the U.S. without returning to Nepal after the expiration of the visa, how does that affect my visa status?? Will there be any complications  for me in the future??

2) i graduate this semester. no jobs yet. Should I extend my studies, even though all courses are finished?? My i-20 expires on may 31, what should i do after that date to stay in status??

Any suggestions from people with above experience or expertise would be Xtremely helpful !!!!!