Ignoring the dismissing caused by a misconception below (this project is not nor was ever meant to be like ‘GTA:O’ at all, it is merely another multiplayer platform on the GTA V systems), let’s take things point-by-point:
The only active websites are https://fivem.net/ and https://forum.cfx.re/ - no other download pages are official for this modification whatsoever, and those that were in the past (literally, only fivereborn.com) all redirect here.
The modification history is fairly complex, however this is the strongest brand traditionally. ‘MultiFive’ was not related to this development group at all, but was a separate splinter group made by barely-competent Russians on the same source code (of the original 2015 FiveM) that this project is based on.
No version of FiveM/FiveReborn ever asked about verifying Steam accounts - Steam authentication happens through authentication tickets obtained from a running Steam client. If other people reupload these files and add malware, we can’t do anything about this.
There is a validation prompt for verifying Social Club login details, this is there because there is no other way retail (disc, SC digital download) ownership can be verified - the window asking about this could be reworded as it scares off less technical people, however being too transparent in this regard can and will make Take-Two/Rockstar take action against this modification, like has happened to the original developers of FiveM in the past (using frivolous claims that could not be defended against, committing more illegal acts than they alleged these developers did in the process).
Onboarding seems to be lacking, however most these people seem to be referred from second-degree or third-degree acquaintances, and therefore won’t provide their feedback on the onboarding process (there’s a lot of things that can go wrong with desktop-based software) to the developers so that these issues can be resolved.
Then, we have some documentation complaints:
This is currently already documented in the server configuration file:
# set to the path of an icon to use in the server browser. it should be square.
#ServerIcon: hello.png
There’s the example resource which was documented to exist in the update announcement, for the lack of a proper documentation service currently.
Documentation is mainly missing as the project itself is incomplete so far - and as documentation, by definition, can only be written by people understanding the system, they’d have to take time from improving the system to write said documentation - for a system that’s still in flux and lacks various minimum-viable features.
This project is currently primarily targeted for early adopters.
There’s no administration system in the server at all currently, other than direct rcon access - documentation for this had existed in past projects but these weren’t archived when our group took over from the ashes of these past projects.
Any community addons are not maintained by ‘us’, so we can not document these.
Both are leftovers from testing, and this capability had only been implemented for 2 weeks when the original project was forced to shut down. Again, we’re doing all we can to recover from this mess that occurred in the past under previous ownership, and that hadn’t improved much under the original ‘FiveReborn’ project.
In the end a typical ‘player’ shouldn’t need or even want to run a server at all. Again, as seemed to be misunderstood, this isn’t a GTA:O clone, but a development platform for allowing modifications for GTA V - the ‘M’ in FiveM stands for ‘modifications’, not ‘multiplayer’.
There are none, for this is a task for the community.
There’s a ‘hands-up mod’? No such thing is included with the project itself.
I don’t see where this project is advertised as having such - there’s no place this is advertised as anything officially; effectively this modification (like those in the past for SA and IV) is a clean slate for people to build stuff on, which is why there’s no official branding about capabilities until the minimum-viable product is fully functional.
The specific protocol shouldn’t be relevant for people to care about at all - needing incoming ports is typical for classical game servers that don’t function through a centralized relay, which would be prohibitively expensive for our purposes.
We’re just a semi-large-sized people spending whatever free time we have on improving this project in a scattergun fashion, releasing snapshots along the way, and somehow dealing with fallout from the past from the publisher and past community attempts to rework this codebase.
If things look like a mess currently, this is part intentional.
проект Λ (project V, written in an intentionally-distracting script) is a temporary name to bridge the transition from the old ‘FiveReborn’ project to the unified resurgence of the FiveM project, further details of which are beyond the scope of what can be reasonably made public.
We conveniently refer to ourselves as the ‘CitizenFX collective’ - an ad-hoc group of like-minded individuals striving for technical perfection in developing modifications for the RAGE-based Grand Theft Auto titles, and attempting to have a bit of fun along the way.
If you haven’t dismissed the project entirely - where’d you first hear about this, and how did they (or the information available on the project web site) influence you toward thinking this?
This seems to be a common misconception, and a new landing page would be really helpful - however our web designer sadly is too preoccupied with other tasks to make one of these.
This project’s code is not related to GTA:O at all, and directly copying these features would only paint an even larger target on our back by having to add various technicalities that Take-Two could strong-arm us for in a court of law.
In the end this is meant to develop on a divergent path from GTA:O and V itself, similar to how GTA:SA multiplayer modifications have done in the past - however for various (legal and other) reasons the project is already 1.5 years behind in development from what should have been the case… again, it’ll be a 
in the end but for now it’s just having to wait and resist the misconceptions in the community and half-baked competition attempts from affecting us emotionally, for we are people after all.