I would say there are a lot more subjects that concern me for full release and for the 3rd year of EA.
Let's start with yours.
1) For Paladin or Monk for the next patch, we don't know what will they implement. Someone's datamining on reddit as you said, was nothing more that finding a monk starting outfit from the bard patch. Nothing else. We have the paladin starting outfit, which is chainmail since the start of the game, so there is no conenction there. We also haven't seen any datamined monk animations. It doesn't mean it's gonna be paladin, but we just don't have something to base suspicion right now, as far as what the next class will be. Paladin is a more popular class, but that could work both ways. Also, plate armor, that paladins would probably benefit from for their builds, is absent from the game all this time, so both monk and paladin have things missing.
2) I honestly don't think we will see multiclassing in EA. But even if we do, there are problems with it, and it's not gonna be the same as in tabletop, since most fan favorite subclasses that make it work will be missing. First of all, for EA, we don't have all the classes, and we don't have a lot of subclasses. The most popular multiclasses like sorcadin or lockadin can't work without paladin, and lockadin doensn't work in general in this game, plus we don't know if it ever will. If Larian does not implement anything from other books, like Xanathar's, then we won't have hexblade that makes lockadins work, and even without hexblade, without things from Xanathar's there will not be a eldritch smite invocation. The whole point of multiclassing to actually become a feature people will want to use, is to actually make sense to use it. I guess sorcadin and clericadin would still work, but still. People that want to multiclass rogue are ok, druid/barbs are ok, but lockadins will get the shaft. These multiclasses are the only way to come close to the power level an actuall full spellcaster gets, using a martial character. If they half work, well, let's hope they don't.
3) For the Reaction system, only a Larian employee has unifficially said that they are looking for ways for it to work, they didn't say they are actively implementing it, or that they ever will. So i would wait for some actual confirmation from Larian for that. As it stands right not, it makes a lot of class features obsolete, so it should get reworked, but again.
4) Origin characters. Boy, where do i even start with this one.There won't be origin characters in the EA. They will come at release. The problem here is not when they will come. The problem is they exist. If an origin character with a tailored backround associated with quests you will experience in-game is the protagonist, they will always, always, have more depth to them than a custom character. That's the way it works. If your origin character can be your protagonist, they have to experience everything a custom character would experience, and their own origin. There is ONLY one way of going around that, and that involves actively making a serious plot that exists only for Tav, if you play a custom character. And that plot would be a spoiler to say anything more. It is something that if it happens, will change the story significantly every time you play a custom character compared to an origin character, so i'm way too skeptical about what they actually did with it. They said they took care of it, but i hope that doesn't mean just an acknowledgement for your backround or if you say you are baldurian. You need an actual, serious plot for Tav themselves, one that the others cannot experience.
And that's my problem with the origin system. Baldur's gate was always about the Bhaalspawn saga, and a special protagonist that exists because of that. The DOS2 origin system that makes every character in the party equally important to the main plot, just makes the custom character pale in comparison to the depth of the origin characters. It goes against the mentality of the original storytelling, and that is my biggest fear about the game. No matter how you try to counter this, if your protagonist is special, then it means origin characters as protagonists get to be special too. The "special" part of the main character is gone, because we have a lot, and that's a different way to tell a story. I am not a fan of it. I will remain skeptical until i see what did they actually do with it.
5) As for full release, the game will be in early access for at least 2.5 years. That is if the game releases during Q2. Since 2022 release was "probably" not going to happen, it means they were getting close. We also have some hints that the game actually is very different from what we see in EA, that is their internal build to test the rest of the game. So March-April-May-June, anything goes and it is possible. I would not expect it sooner than March or April, and there is a possibility we even have another year in front of us, a dreaded thought i don't want to be thinking about. As for the people that outright say that they should take their time to finish it as long as it needs, well it doesn't work that way. Too soon is bad, and "taking your time" is also potentially bad for a game. We know games that had all the development time in the world, and how they ended up. Waiting for the sake of waiting for something better, or "the later it is, the better and more polished" mentalities, yeah it usually doesn't work like that. You need a target date and to work for that. Whatever you do , bugs will exist, and game breaking ones at start.
Anyway, this is getting really long.
I am very hopeful about BG3, but also very skeptical. I want to play the game and experience it, but at the same time, not playing as my favorite subclass or multiclass combination makes me somewhat less interested. It also makes me wonder how come companies like Owlcat implement so much more classes, prestige classes, archetypes and abilities/spells for a much more complex system, but according to Larian "it's so much work". I also don't like the origin system, and i am not thrilled so far about the armor designs i've seen, noting of course, we haven't seen most of it. Put the infamous Larian thing about making a lot of NPC only gear that the player can't get-although they should COUGH DOS2 paladin armor, blackring armor COUGH, and you can get "worried" pretty easily, especially with the lack of communication, although it's an EA game, so you would expect something more.
Anyway, i hope they have something to say at some point. This is BG3, it's big for some people, they have been waiting for a BG game for 20 years. We all want it to be "right", and that can be a big pressure on a company.