One of the things I'm probably the most confused about when playing OOP is if I should check and let him CB or if I should donk.

I'm talking about the normal pots.. not the 3bet or higher ones.. altho I would also like to hear about the 3bet pots.. I understand the adv donking in 3bet pots but what about when you have a game flow and he calls a lot of your 3bets since you are 3betting a decent amount?

I see most people are checking in just the raised normal pots OOP and I'm guessing it's because it's the most played pots and because you called his raise but when you have a 3betting game flow where you play a lot of 3bet pots then that's going to become kind of normal pot like the regular raised pots? and then 4bet pots (deep) becomes the next level what 3bet pots used to be?

So what are advantage and disadvantages of donking or checking mainly in normal raised pots but also in 3bet pots when you play a lot of those pots?

lets decide on a definition of donk betting "betting into the preflop raiser when you are out of position"
Here: some times you might consider donk betting;
1)You call raise OOP with A5. Flop comes A72.
Do you donk this flop with top pair? Betting allows a player with no equity to fold when he would likely have cbet had you checked. If he has middle pair you may get some value, but is he really going to call OTF and again OTT or river? But any hand that will call you if you bet would almost certainly bet if you check, but now you can't trap them into 3 streets+action.
And what if you're raised? Well then your just lost in the hand. Are you really going to bet/call flop turn and river with top pair no kicker?
So its not good to donk bet here; Probably you want to x/c flop and x/c turn as standard, (if turn goes x/x then bet river).

2)You; K8 Bttn raises and you call.
Flop is A98
You donk bet. Opponent raises. Now what? Does he have a straight or flush draw? Does he have a nine or an ace? Is he raising because he's got a lot of aces in his range, or JUST BECAUSE YOU DONKED AND PEOPLE LIKE TO DONK BET MIDDLE/BOTTOM PAIR (that's the biggest trouble for me. If you donk and get raised its so hard to interperate the raise because your range looks polarized but you don't know if opponent knows that) So, say you donk and get called. The turn is a Q. Now what? just bet again, essentially turning your hand into a bluff? Or you could check/call and hope opponent doesn't have strt, bigger pair, or a hit a flush. Even when you bet out, get called, and the turn and river are both bricks your gonna be lost.

When you have a mediocre hand you don't want to donk bet cause you'll be called by better hands and worse hands will fold. Plus you may allow a player to raise you and cost yourself an entire pot.

When you have a strong hand you don't bet out because you want to let your opponent bet out so you can x/r him and trap him for a big pot or just x and call him down and let him bluff off all his chips.

When you are weakish with some SD value your goal should be to see the river as cheap as you can, betting doesn't help that goal.

If you have a strong hand and opponent has a stronger hand you will save money by xing and calling
If your hand is stronger you dont discourage your opponent from barelling for value or as bluff.

Poker is complicated enough without adding a whole subset of ranges to ballance. If you start donk betting some hands, how do you balance it? Will you have a donk bet range and a x/raise range?