After a bit of searching and consulting the FAQs on here, I've finally managed (or think I did) to un-mix Strike Ranged and Strike Missile. (Maybe it is because I'm not a native English speaker, maybe it is because the terminology is an incredible mess...)
Despite Ninja & Superspies listing the bows, crossbows and slings, as "Missile Weapons"... it would appears this no longer stands true for RUE and RT2. Rather, what we find here is that HtH bonuses includes mentions of thrown weapons and *gasp* guns!
According to W.P. Targeting; "Missile Weapons" would be anything that its W.P. indicate as built for throwing. Thus, I guess that "Missile Weapons" comes with the "Strike Missile" and concerns things such as lances, knives, hatchets, etc... No longer related to N&S missile weapons, now under the W.P. Archery with harpoon guns, and as such dependable on "Strike Ranged".
So correct me if I'm wrong but... This would mean that a bunch of W.P.s leads to Targeting, specifically "Missiles weapons" according to that same W.P., that should be related to the "Strike Missile" column on the character sheet HtH's table, itself referred to as "bonus to strike with thrown weapons" in HtH. Furthermore, W.P. targeting needs another W.P. as a "requires" section, and thus cannot be a skill on its own.
Meaning that these weapons would use the bonus to P.P., but not P.S., and the "bonus to strike with thrown Weapons" (Strike Missile) in addition to their own W.P. AND Targeting if available, when being used. (???)
With on the other hand W.P. Archery, useful for ALL Ranged once missiles weapons, not leading to W.P. targeting, that should be related to the Strike Ranged column on the character sheet. Said weapons containing some "guns", or at least frames using a rail above a trigger, would also benefit from "bonuses to strike with guns".
These not benefiting from P.S., P.P. only for bows and crossbows, and such Strike Ranged Bonus (HtH guns) additive to their own W.P. (???)
First Question : Is the above correct?
Assuming that it is... and I hope it is because it sounds confusing enough... (Why not use the same terminology from one part of a rule to another?)
Then this leads us to the...
Second Question : Why isn't there any Weapon Proficiencies for Slings or Archery in Robotech?
In the extreme, i kinda can understand why the sling isn't there. It mostly makes the thing harder to learn, and maybe the GM assuming that targeting is enough might solve this. Though Targeting is clearly stated to be a following up on the training of another W.P., and as such asks for a skill that isn't there. So a GM might want to create it. Which wouldn't change much considering RUE offers it as a simple line referencing Targeting.
The really frustrating part is the Archery. That must somehow be equated with guns (Strike Ranged)... or would be apparently potentially less accurate than throwing knives and hatchets. Especially since real guns aren't normally receptive to physical bonuses, but archery would be one of the rare links to the Strike Ranged bonus called guns in HtH.
And since this isn't in RT2, we kinda not really know if the bonus to guns, from HtH Assassins, is related to anything on the character sheet.
But it gets worse.
Third Question (S... SSSSSSSssssss):
A Praxian Warrior R.C.C. is built in with the W.P. Targeting as per the UEEF source-book. It also receives, as a cultural specific weapon, a BOW!
But no mentions of a W.P. Archery. The W.P. Targetting might be used to throw the blade staff, which is apparently only used for "missile strikes".
But then, if one gets to the staff to know this, one also finds the only stats for the loneliest bow of robotech.
Which, as a rate of fire, indicates : As per archery and targeting skill, otherwise each shots takes two attacks per melee for unskilled users, and range is half.
WHAT DOES THIS MEAN???? Where did I go terribly wrong?

What am I not getting between Targeting prohibiting Bows and Arrows, and yet being proposed as a source of a non-existing ROF stat,
for an alien weapon that could, for all intent and purposes, work differently than all other bows?
Is the lack of archery a joke subtly indicating that no Praxian knows how to shoot, despite being gifted with it at birth?
I guessed that the reference to the Targeting skill was so that we'd know ancient weapons do use the P.P. bonus to hit.
But from there on out, it really does nothing to help. Even ignoring that Targeting is prohibited to boost the Archery skill,
it would only give +4 to strike at maximum, and would offer a ROF of one melee action per attack, shooting faster than a bow from RUE can.
Comparing to RUE's Archery giving a whooping +8 at maximum, a bonus to parry with the thing, and a starting ROF of 2 per round until the levels comes home.
Ah... and a trained archer increase it's range per 50%. The maluses being otherwise the same for the bow and targeting.
How am I supposed then, to read that the Praxian bow, of which the specificity seems to palliate for the lack of Archery,
and which refers me to a prohibited use of a skill and a non-existing one?
Should I import Archery from RUE to correct the missing piece? And if I do so, would my Praxian bow gain 50% range above its 150 or so meters?
Would it stop being so slow to fire eventually? Should it, in the face of game balance?
It is an Alien Bow after all... Or are these descriptions here to palliate to the absence of the W.P. Archery???
Meaning that the Praxian Bow would have such a range to the initiated BECAUSE it factors the 50% range in?
And that the sourcebook is contempt to send us toward W.P. targeting, BECAUSE the slower rate of fire at the beginning IS to the uninitiated?
What does a W.P. Targeting mentions does into the description of a Bow? Is that bow a Missile Weapon in the sense of N&S?
Why not just offer the Archery thing in the UEEF manual, if it was important to do so by this point?
Why does a cultural weapon do not see it's W.P. given, in the same R.C.C. that pushes the weapon on an unsuspecting player,
soon to go play "fetch" all over his library?
Am I missing anything here?