If you have trusses, which it sounds as though you do, you cannot modify them without either the original mfgr approval (good luck finding out who they are) or an engineers stamped plans.
Although people use the attics formed by trusses for storage, they are limited to light duty storage, such as Christmas decorations, luggage, etc.
Modification of trusses, such as cutting chords, removing webs. etc., will cause your next house insection to fail, about the time you were hoping to sell. Don't do it without proper review and approval.