Question – If an F- student pursuing a Ph D degree is

1. If an F-1 student pursuing a Ph.D degree is unable to complete his study by the program end date on the Form I-20, and is granted an extension by the DSO, must he apply a new F-1 visa ? Whether he can continue to stay till finish his study without applying a new F-1 visa ?

2. If he will do post-doc research after his Ph.D program, is his status F-1 or F-1 OPT ? What is the best way for him to maintain his status in the US ?

Question – I am a US citizen thinking about bringing my mother

I am a US citizen thinking about bringing my mother to the USA. If I start the application process here in the US, will mother be allowed to enter on a tourist visa and stay will be and then go back to her country of residence for her interview? Will her tourist visa be automatically suspended while she is getting an immigrant visa?