Actually fairly easily, the new weapons and shields/armor balance out very well against one another, its just another step up in technology that wasn't there in the previous game and adds a bit more interesting tactics then.
Shield Depleter+APB=ultimate combo!
The I-Las is basically just a lot more expensive and more powerful version of the APB that works really well against phase shields and below but only about average vs void shields.
As far as the ship sizes goes, well everyone gets the same ship size