Actually, I would like to have the grid on the top... then below the grid, several controls to display the details of each records in the grid... while you selected from the grid, the underneath controls will refresh themselves... it is very classical to human resource management software...

Go to next page?! not good idea! The users will be blind if they keep doing that...

open a new window if you have problems on space. Also, it is better to open a new window if you're going to something else than before, e.g. append a new record... seem more logical to me that every new window means new function, in software engineering -> more money...