You will need to conform your original film negative to the video edit. You will then cut the negative and strike prints the usual way.

In general the DP will chose what stock to use based on discssions with you, the director. But if you're going to shoot it yourself then you'll need to learn what the different negative stocks can do. Are you shooting the film yourself?

Plus X isn't a negative stock. It's a reversal stock. So I'm not sure what you mean what you say you don't know what negs to use. Maybe that's why you're confused. You aren't using a negative stock at all.

When making release prints it's best to shoot on a negative stock and not a reversal stock. Negative stock is used to print multiple positive prints - the negative never runs through the projector. Using a positive (called reversal) stock makes making prints much harder. With reversal you run the stock through the camera, get it developed and then run that same stock on the projector - projecting the original footage that ran through the camera. With a negative you run the neg in the camera and then make a print (called a "workprint") that you would edit. Now-a-days there is no need to make that workprint. You develop the negative, transfer it to a digital format and edit that. Then you conform from your EDL to the negative. Once the neg is cut - only that one time - many prints can be made of the final movie. You can do the same thing with reversal stock but a positive to positive print loses quality - that's why people shoot negative.