Vintage ~1975 Datejust - Real or Fake?

[LK0621]

I found my dad's old Rolex - was a gift from the mid-1970s. We think it's real but can't really tell (he threw away the packaging decades ago and along with it and official certification). I'm planning to take it to an official retailer when I have a chance but not sure how much they'll know about a 35 year old watch. It's also busted - so I can't tell what type of motion it has.

Questions/observations:
1) It seems to have a plastic face. Someone said it's acrylic which apparently is what Rolex used back then. Is that right?
2) There are holes where pins attach the bracelet to the case...I don't have these holes on my own Rolex (which I know to be real).
3) A friend of mine has some Rolex tools for removing the back of the case - but didn't have on that fit this watch. Is that a sure sign that it's a fake? Or did they have diff't gauges 35 years ago?