"""""""For example, I want to select this section to put a different material than the body and so on but it would take a lot of time to select every triangle of that selection/edge to have a clean selection of that surface. Is there a workaround?""""""

You can select those areas in MoI "FIRST" and assign it a material and an object name.

These should transfer into your poly app through obj for "selection" or whatnot.