Only have the core book and was wondering if there are better throwing weapons than knives. Also do non-grenade throwing weapons use the ranged weapon or melee weapon quality benefits, looking for RAI not RAW.

Define "better". Historically, or at least from what I've observed, Thrown weapons get the least love of any weapon class. Off the top of my head, [into the Storm] has throwable metal disks, electric disks, power discs, chainsaw disks, and javelins. [Hostile Acquisitions] supplements those with shock balls and shock nets. [Faith and Coin] has a pseudo-throwing weapon in the form of an atatl that buffs javelins. All those books have extra grenades as well, if those also strike your fancy.

Outside of the written weapons, throwing hammers, axes, darts, needles, and the like exist in other settings or other games entirely. And in history/reality, for that matter.

I am not sure I understand your second query. Do you mean Craftsmanship benefits? In the aforementioned books, the thrown weapons are listed in the melee section and certain weapons are eligible for the Mono upgrade. As well, thrown weapons are of a contact-based, multi-use, and, depending on the shape, can be used as melee weapons in a pinch. If I was a GM who actually used the Craftsmanship rules as written, I would personally consider thrown weapons as melee weapons in regards to the benefits.

You missed [stars of Inequity] which has Javelins on the archo-xeno tech chart, which can get rather awe inspiringly effective.

Personally, I'd allow the player to have either type of upgrade, so long they could reasonably describe it making sense. For Good/Best quality, I'd let the player pick one or the other (or both goods as a best) depending on the bonus they'd prefer.

My Missionary has taken to throwing his Witch Lance at people whenever they try to stop combat to have some good old fashioned exposition. It's also his go-to test to see if someone's a Psyker or not.

Into The Storm has the Crimson Crowns and Power Discus, which are Chain/Power Throwing Circle that probably requires you to trill like Xena when you use it.

Stunspheres and Shocknets from Hostile Acquisitions are amazing, because they force a Shocking test even if they deal no damage . Arm a group of thirty armsmen with three apiece and you can incapacitate any enemy coming your way. Or PCs that are annoying you.

Flying Claws are fun if you want to make Warrior Monks, since Snaring characters can be an underrated tactic.

There are a few in here which are not terrible. Thrown weapons dont usually get much love though. Many people would make a good argument that most melee weapons would simply not be useful in a galaxy of guns, and thrown weapons are below even those.