do i try to get the best armor from instances like the false emperor or do i try to get the pvp armor set.

1. Someone told me you can carry an orange item throughout the levels and all you have to do is keep adding mods onto it to keep it up to your level. is this true? 2. if that is true then what is the point of blue and green armor if you can just mod the orange ones to be better? 3. is synthweaving even worth it if orange items are always better than them? i might have all of this mixed but i would like to know before i level any further. (also is purple better than orange, and how is it?)