Hector,
1. yes it can be set globally, WebServer procedure, defaults, Browse and form tabs.
2. Yes it can be set locally, as Alberto's pic shows. (I recommend using Grid mode).
You can't change from <table> layout to <div> - grid layout using CSS, no. The layout has to be set first then the CSS comes into play.
Oh - and I'm not sure if NT11 supports Grid- that might be an NT12 thing, in which case in NT11 use Div-Flex. It's not as good, but'll get the job done.
cheers
Bruce