Those questions don't have cut and dried answers - they can depend heavily on where the work is.
Spool fabrication shops prefer traditional piping isometrics. They normally redraw the pipe runs in dedicated spool construction software like ACORN or SPOOLGEN anyways, but can save some time if you can provide accurate PCF files that they can import as a starting point.
Fabrication shops, especially those dealing with skid mounted or package type modules, tend to prefer models over drawings. Depending on their software of choice you may be able to send a project as-is, but you may need to send neutral format files such as IGES or STP. Like spool shops they may prefer traditional iso's and PCFs for pipe runs, but its common for them to not do any traditional iso's at all when using Inventor, CATIA, or Solidworks.
Clients requirements vary wildly, sometimes depending on when a project was started. Some only want a functional, data-rich model but in a specific program and version; others only want issued GA drawings and only want "throw away" iso's for construction support; others want both GA's and iso's signed and issued. More frequently they're wanting models from Navisworks or similar software for review purposes.
Field construction wants paper drawings; typically this is GA's for site-assembly plus iso's for use as punch-lists and marking up when something doesn't work right. They're also getting on the Navisworks train - we have site photos from several projects where someone has printed out color screenshots and taped them up so the crew can see what it should look like.
Short version is - at the START of the project determine what the deliverables and requirements are. That includes program and version, data/file types and version, what the client requires, what the fabricator requires (if you're doing the "M" side of EPCM), and so on.
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If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.