1. If student transfer college then h/she do not need to go for stamping as long as h/she is not travelling abroad and do need to worry about visa expires as long as h/she maintain status (doesn't matter F1/H1/J1 etc or got changed).

2. If you have valid visa and you are on the same college then you don't have to go for stamping.

That is what I know and that is what 4-5 years ago. I have no idea if rules got changed. Why don't you consult your international advisor when you get admission or consult your current Int Advisor.