Customizing debrief screen on laptop

Hello,

We would like to resrtict the LOV's for the Service Activity Codes for Labor and  Expense tabs on the debrief  screen on the laptop using some attributes(Conditions) and then also restrict the Items LOV based on the service activity codes on the LAPTOP

Here are some of the questions which I need clarification on how can we do this

1) Can we customize the standard debrief page on the laptop ?

2) I found a metalink note 248063.1 which talks about the customization and the SDK...The note says we can create new screens but cannot  modify the screens on the laptop like add columns, hide columns or re-arrange columns but it does not say whether the code behind the form can be modified or not?