> clocks tick slower under the moon's weaker gravity. (Or is it faster?)

Compared to clocks at rest on Earth, clocks on board Orion right now are ticking faster, because it's at a high enough altitude above the Earth that the faster ticking due to higher altitude outweighs the slower ticking due to speed relative to the Earth.

That will be true for most of the mission. For clocks in orbit about the Earth, the "breakeven point" where the altitude effect and the speed effect cancel out and the clock ticks at the same rate as an Earth clock is at, IIRC, about 1.5 Earth radii. So clocks on the ISS, for example, tick slower than Earth clocks; but clocks on the GPS satellites (orbiting at 4.2 Earth radii) tick faster (and there is an adjustment made for this on each satellite so that the time signals they send out match Earth clock rates).

For a spacecraft moving at escape velocity, which is going to be roughly true for Orion all the way until splashdown, I think the "breakeven point" is higher, at a little over 2 Earth radii. Orion will reach that point on the way back a few hours before splashdown, I think.

The Moon's gravity well is too shallow to make an appreciable difference in any of these calculations.

I should emphasize that all these tick rate effects are tiny, on the order of one part in a billion to one part in a hundred billion. Even when you add up the difference over the entire mission, it's still only on the order of hundreds of microseconds (i.e., the astronauts end up aging a few hundred microseconds more than people who stayed on Earth).