yup, planning stage is the most important kay lisud na kaau ma sayop. exchange 2003 is just an extension of AD. AD ang magdala ug bida ana. dali ra mag implement if your plan is well layed out.

depends bro if mo sugot ang HQ which i doubt. do you have a dedicated connection to their AD?

Please ask advise bro sa HQ, i think mas makatabang sila sa imo plan.