Pex plumbing is a low cost plumbing solution to the theft of copper plumbing. Pex plumbing also has ability expand which will lower the risk of the pipes bursting. Pex is not the most attractive to look at but it will get the job done If this property is a rental I would not waste the money on cooper plumbing. You can save the money and put in into other parts of the home. You want to put the money where you will get the biggest return on your investments, which is kitchens and bathrooms.
As always, have these installed by a licensed professional.
Plastic that is approved for plumbing in the areas you'll be using it should be fine. Just make certain that it is approved, especially if it runs in any unheated spaces like a crawlspace or garage.
If you're using a licensed plumber ask him to refer you to the manufactures site where you can research the product and satisfy your concerns.