Rotate2, I've tried replying to your pm but it says your inbox is full
Afraid I can't be of much help tech wise as I'm far from an expert, just go for the best graphics card and fastest processor you can afford.
As for add ons the Zibo 737 is a free upgrade is the one you want. There are many other excellent utilities and add ons available, I suggest you have a good look around
https://forums.x-plane.org/ and ask any questions on there, there are people far far more knowledgeable than me
Hope this helps