What's the best way to clean dust off X-Wing (series, not necessarily the ship) figures without damaging or breaking the figures? As much as possible, I prefer not to use chemicals.

I've always used a slightly damp small paintbrush to get junk off my models (X-Wing and others). For the GR-75 and CR90, I just used a regular dust cloth on it after removing the radar dish and turrets.

Just dust? Compressed air, or wipe with a dry lint-free cloth (i.e, not a paper towel or tissue).

If that doesn't work, a moist cloth (water only).

If they're too dirty for that, rinse with plain water.

If really dirty, you could gently wash with a mild dish soap.

The paint isn't going to rub off, it will take some decent strength chemicals to take any paint off.

Man, you must not play with them enough if they have time to get dusty! (Or maybe I am just a bit obessed... probably the latter haha)

Seriously though - if I have miniatures that need a bit of a clean up either my airbrush compressor and/or a damp cotton bud is usually enough to get the job done.

x wing stays in a case, but have lots of figures from other series we don't want to wipe with damp cloth.

The mrs came up with a good idea of using an unused makeup brush (one of them big thick ones) as gets rid of dust in all low spots too, should work the same for the ships

You are not going to mess them up if you wash them in hot dish soapy water. Just run a sink full and use something like DAWN because that removes grease. Kind of swish the models in the hot soap water, then rinse them off good and just let them air dry on a towel. I would not scrub them or do anything with a rag or some such.