I'm going to mark this topic Solved guys, I have answered the initial question satisfactorily and have not wondered massively from the OP. I will open another one to ask all my modelling questions. Again, massive thanks guys, your help is hugely appreciated.
Initial question: How much stress do FX put on the game?
Answer: Loads. Excessive FX use or excessive FXParticalSystem use in particular causes the game to lag or even potentially crash. Apparently some FX put more stress on the game than the models they are actually attached to do.Go to the full post