Rewrite Rule in Nginx

Question

Hi.
I conisder moving to Nginx but I want you to ask if is possible to rewrite urls into that schema, and if you could help me a bit:

• A url like http://example.com/username into profile.php?u=username. But then, will I have problems in accessing other pages like e.g. home.php
  

• A url like http://example.php/questions/102039/that-question into questions.php?quid=102039
  
  Thank you very much!