Yes on the x39 bolt. I asked Alex about using a type 1 x39 bolt and he was pretty adamant(without giving details) that RA wouldn't recommend that and they would only ship grendels in type 2. That was years ago and I've never followed up and I haven't tried it myself.
I've been using the elanders and they've been fine. By no means hard use though. The 24(?)rders I've got have all been 100% fully loaded in an AR and XCR so far.