So, arachnids appear to not spend any points when they level up, but they do gain HP and FT with every level. Do any of their hidden stats (damage, armor, healing strength [medical arachnids don't use the healing tech skill]) improve? Or do some of the others (regen rate, etc) improve with more level gains?

If not, leveling them up doesn't seem to be worth all that much: a medical arachnid gets +2/+2, which means that if you got it to 50, it would only have +50/+50 (starts at 25%), an 80% boost to health and 50% to fatigue (and therefore maximum healing capacity).

Thanks. Mine (well, the med. arachnid) is level 25; are they L30 or Normal, or is it just that the medical ones are naturally lower level, if you know? (enemy standard arachnids are L30, but I've never seen an enemy medical . . .)

Sorry, let me clarify: Arachnids are l25 by default I think, only Automatons are l30 by default.

Not to hijack the thread, but on the subject of Medical Arachnids, I just got one from Maxim. But what do I do with it? Its just sitting in my inventory.

Put it in a quick slot then activate it.

Put it in your quick slot, then "Throw" it like a grenade. (Do not throw in the direction of peoplr or pets as you can hurt them this way :) It will walk around healing and fighting. Like Diablo 2, if it gets too far behind, it will teleport back to you. If you go on a ship, you will have to pay for it. But if you pack it up and put it in your bag you do not. Same for other robots.