Well welcome to the club mate! orks are definitely one of the funner armies out there (and da best).
As far as your list(s) go there are some things you could do to optimize, but its largely dependent on how casual or competitive you are wanting to play so what I'll do is just tell you everything you can do to optimize and then you can decide what you want to do from there.
HQ - Painboyz - are fantastic and an auto include in every list for me
Weirdboyz - are pretty meh unfortunately. Apart from the +1 attack for the squad blessing, everything else will likely either kill him or get denied. If you decide to keep him I would put him in a 30 man blob of boyz with a painboy, make him ml2 and hope you roll that power, which if you do will give your boyz 150 attacks on the charge (and nothings funner than rolling buckets of dice).
Warboss - also an auto include for me. Give him mega armor, the lucky stikk, and a cybork. He is super durable and killy against most things. I usually throw him in a blob of boyz that way they get ws5 and he can tank wounds up front, but he's solid pretty much wherever you put him.
Elites - Burna boyz - unfortunately are also kinda meh this edition. Their great if you can get them to their target, but most players will probably dedicate enough firepower to make sure that won't happen. Also a bit pricey.
Mega Nobz - are fantastic. Kit them out the way you did in a trukk and flat out turn 1 (also called the
MANz missile). I would give one of your models a killsaw. For 10pts it gives you 5 attacks on the charge and armor bane, which means you'll be wrecking pretty much everything short of a super heavy vehicle on the charge.
Tankbustaz - also solid. Usually there's 2 ways to kit them out, either a small suicide squad in trukk or a larger one in a battlewagon. Suicide squads are great if they make it to turn 2 because they can pretty much strip the hull points from any vehicle or super heavy possibly for dirt cheap.
Troops - Boyz - are the core of your army. Trukks are unfortunately a death trap for them this edition, which leaves you with either putting them in a battle wagon or foot slogging. I prefer the latter personally because I can't justify spending almost as much on a transport as I did for the squad itself. If you decide to foot slog I would make them around 25-30 man strong with a
bp claw nob and painboy. If your good at utilizing cover they are ultra durable with a 4/5 + cover and then 5+
fnp.
Grots - are clutch. I very rarely leave without one or two squads of these gubbinz. Their super dirt cheap and fantastic at coming in from reserves and camping on your rear objective. Seriously, these guys are workhorses at winning the objective game.
Fast attack - not much to add here. solo deffkoptas are a good choice for grabbing objectives and staying under the radar. Be careful in kill point games though.
Heavy support - Lootas - are solid. Usually I would put them either in a battle wagon or behind an aegis defense line, but whatever you have in mind will likely suffice.
Gorkanaut - their fluffy so its up to you if you want to keep em. If you already have the model then I'd keep him. If not then I'd likely drop him to max out your boyz squads and add a squad of grots.
LOW - Ghazzy - not worth the points super unfortunately. Unless you are going to run the new ork decurion detachment, a megaboss with the lucky stikk will do his job arguably better for 100pts less, but again since you are going more casual to start with he is still a decent choice for fluff alone.
Anyways hope some of these tips help. Let me know if you have any questions, I'm happy to help, and welcome to the waaaaaagh!
