You should read the book. It makes things more clear and is actually a very enjoyable read imo. 
The 6 dune books go well beyond this story - so there is a larger arc to it - which I am currently reading - so I don‘t know too much about it other than then Keynes prophecies might come true.

The are shields and laser guns- but those don‘t mix well as it creates a nuclear reaction of some sort. So back to projectiles (bad against shields) and knifes. 

Can you synthesize gold, no? Why?

Everyone fights because it‘s all about power and resources. Much like on earth. 

Paul might appear more invincible in the movies - not sure. He is actually kind of growing into his powers and skills in the book - not a homerun at all. 

 Nice rebuttal. Books always trump the movies as there's not enough space to fit all the detail.