Tiltskillet

I can provide you a list:
https://warframe.fandom.com/wiki/Passives/Weapon
You didn't say it had to be an even-remotely-close-to complete list! :P
Here is an augment list.  Unfortunately, like the above, it's not just melee.  But I think it's at least fairly comprehensive:
https://warframe.fandom.com/wiki/Weapon_Augments
 

Duplicate definitely seems to help Shattering Impact on Sarpa.   Without it, I couldn't strip a SP Corrupted Lancer Eximus in under 19 bursts in five tests.  (Once it was 20, probably because of inaccuracy.  In theory, it should be the same number of bursts every time.)  With just a rank 0 duplicate and ~76% crit, so only about a 19% of a Dupe proc, it ranged from 15 to 17 bursts.
I'd be even more comfortable seeing a test involving a R5 Duplicate just to verify that it's scaling as it should.  But that's pretty solid evidence on its own.

There are many, many  weapons I haven't tested or looked at.  And when I've been looking closely, I've almost entirely been concerned with bodies--landscape may impact some of them differently.  I also haven't looked at ricochet or chaining AoE with PT.
Anyway, such as they are, my observations are there are four different behaviors: 
 - PT Projectile stops at first target, explosion originates from first target.  The vast, vast majority of projectiles that carry a radial damage component haven't been affected by Punch Through at all since Veilbreaker.   Nearly all still display a PT value in the Arsenal if modded for it, radial beam weapons being the only exceptions I can recall.   (Whether they punch through or not.  See below.)
 - PT Projectile continues past first target, explosion originates from first target.  Ferrox regular fire, Trumna regular fire, Opticors, Scourge Prime throw.  I think there are a few more I can't recall, and no doubt some I haven't discovered.  Most or all are weapons that have always had innate PT. (Scourge Prime is particularly bizarre, as its PT is undocumented,  it seems counterproductive, and the basic version doesn't behave this way.)
 - PT Projectile continues past first target, explosion originates from last target.  Komorex altfire, Mutalist Cernos, Ignis.
 - PT Projectile continues past first target, explodes on multiple targets.  Sporo with augment.  I feel like there's an Incarnon weapon that does this too, but not one I've tested personally.
I could have sworn Ignis was put in the "non functional PT" pile at some point.  But I just looked at the Wraith right now,  and the beam is punching and the sphere originates from the last target hit exactly as you described.  OTOH PT on Primary Gaze does nothing to either the beam or sphere.   I haven't tested the others.  I would have bet this whole group worked the same way as each other, and I would have lost that bet.
Another odd inconsistency is Torid (non Incarnon) vs Mutalist Cernos.  Non functional PT on the former, last PT contact explosion on the latter.
 

It's the same weekly cycle as Archon Hunts, yeah.  The rotation is set and always in the same order. (At least until they add new ones.)  So you'll have a week for Soma, the week after that will be the Stalker weapons...and Torid should be back on 20 Nov, if I'm looking at my calendar right.
You can see the rotations here: https://warframe.fandom.com/wiki/Incarnon?so=search#Reward_Rotation

Drop chances can be found in the wiki usually.  https://warframe.fandom.com/wiki/Redirection
It looks like Cetus Bounties would be the best choice.  If we're on at the same time I'd be happy to give one to you, and probably some other shield mods.  (I tried messaging you just now, but I think chat servers are down.)

Still bouncing for me in the Sim, both off terrain and enemies.  And shooting at feet still gives the ridiculous multiple explosions.
I didn't try to check falloff.

Valkyr with her Paralysis augment is my favorite way to get a lot of ground finisher kills at once.  Knocks enemies flat, sucks them into a small pile, and keeps them there for a long time (with Strength, not duration).

This is a good resource: https://warframe.market/auctions/search?type=riven&weapon_url_name=attica&polarity=any&sort_by=price_asc
Maybe the first thing to look at is whether a weapon is in demand or not, and therefor whether rivens for it are as well.  I'd have guessed the Attica wasn't, and that seems borne out by the low price for unrolled Attica rivens and the amount of time some of those have been sitting for sale.
Even unpopular weapon rivens can command decent prices if the affixes are right.  In the case of your riven, Status Duration is generally seen as a waste.  Toxin can be very desired in combination with other good affixes.  Damage can be desired, but mostly in the case of AoE  or upfront damage weapons, which the Attica isn't.  Negative Projectile Speed, particularly in amounts more than 60% is a serious drawback for a projectile weapon like a crossbow. (It is a terrific negative to get for a weapon that's hitscan and therefor unhurt by it.)
So, no, I don't think that roll will be worth the kuva you spent on it, and is probably not worth continuing to burn kuva on.  It'd be a different story if you loved the weapon.  But for trading? No, I wouldn't recommend it.
There is a vast amount of information to absorb when it comes to riven trading.  I think I'd recommend trading simpler stuff to start off with.  And then as your familiarity with the game and with the market grows, start dabbling in rivens more.  I hope this doesn't sound patronizing--I have huge amount to learn about the subject myself.

KHek has a dispo of 0.9, Hek is 1.2.  0.9 / 1.2 =  0.75.  So that is the correct multiplier and the affixes scale down as one should expect.
I'm not sure exactly where you went wrong, but it probably has to do with using pips/range rather than exact dispo values.  Those can be found on the individual weapon pages in the wiki.

Lots of options, but Valk Prolonged Paralysis is what I use for ground finisher builds.  It brings enemies in a mass, and puts them at your feet for a good while.  And best of all, it's virtually guaranteed not to kill anything on its own, lol.
There are more suggestions in this thread from yesterday:
 

A personal favorite for mass ground attacks is Valk with Prolonged Paralysis.  But lots of abilities and melee combos do this.  As well as just simple slam attacks.  Prolonged Paralysis is just very convenient, because, well, it's prolonged. :P
Keep in mind ground finishers aren't simply meleeing an enemy on the ground, but  special custom animations.  They can be hard to execute sometimes, especially in squads. I'm in the habit of ADSing when I do it, and I remember vaguely that it helped some when I first started using them.