Right now, the vast majority are on DVD-9, whether they need to be or not.
For the most part, it's on a company by company basis. Some companies put everything on DVD-9, even on short productions, others put everything on DVD-5, even if it causes them to overcompress.
Nothing can be copy protected. Unencrypted DVD-5's are currently the only ones that can be copied using "off the shelf" DVD burning software. But there are lots of programs out there that can be used to derypt and/or re-encode DVD's to a lower bitrate.
All replicated DVDs (discs that are manufactured, not burned) can be copy-protected for a fee with either CSS encryption ('content scrambling system' to help prevent digital copies) or Macrovision (to help prevent analog copies).
The amount of discs you intend to produce plays a part in determining how cost effective copy protection may be. I'm not sure what the current going rates are for this but if you check with your replicator you can get a solid figure.
Both of those methods can be easily defeated. CSS worked well until some company screwed up and didn't secure that decryption key properly. Once that became available, CSS became nearly useless.
Since the initial question has been answered and this thread is heading into the direction of an inappropriate topic for ADT, I'm going to lock it.