Question about pot odds

So I use the 2/4 rule to get a rough idea of outs and I've been trying to play pretty robotic at the micros (finally got a bit from a freeroll so it's all absolutely the lowest limits possible).

I know if the chance of hitting is a higher percent than the percent you pay to win the pot you make the call. but what do you include as pot? (these are high since i'm doing 2c/4c but its easier with whole numbers) say pot is 2 bucks. I'm sittin on 2 hearts and 2 on board. so 2/4 says thats 18% i'll hit turn. so is the max call 18% of 2 (.36) or do I include his bet too? guy bets .45 so pot is now 2.45? making the .45 roughly 18% of the "new pot"?

and how do yall use pot odds when deciding a first bet into a bet (post flop)? do you try to figure his draw and slightly outbet what his pot odds would be? or bet using your own pot odds (like i see flush draw so i bet 15% to give under 18% odds)

You view it as your chance to hit on either the turn or the river when you're working out if a flop call is correct (by the odds).

So 2 hearts and 2 on the board leaves you 9 outs. Applying the 2/4 rule you do 4*9 = 36. 36% chance so you can bet 36% of the pot (not taking into account implied odds).

You take into account the total pot, the $2 and his $0.45 so yes the pot is $2.45 therefore you can call $0.88 and be playing a mathematically correct play.

If I have a strong hand I am thinking about his range and what he could have to beat me and the chances of him having it rather than what % of the pot to bet. In micro stakes they won't check the pot odds so if you have a hand go for 3/4 of the pot imo. You'll get plenty of calls with less hands as a lot of the players don't use pot odds.

If you're trying playing for a flush/straight you could calculate your max % play and bet that and hope for a call.

Always make them pay over the odds for flush/straight draws if that would beat your hand. Then they've made a mistake and overtime you'll profit from these mistakes.

People's ranges contain more than flush draws and straight draws.

You can win more than the pot when you make your hand, you can win additional bets. If the player's range is strong, you have good implied odds because the chances are they won't want to fold their hand. If their range is weak, raising with a draw is going to be preferable than calling down.

Of course, I was just using that as an example. Pot odds should be used for any hand you can potentially make in the future (providing the hand wins the pot)l

Yeah, I realize that at the limit i'm playing online doesn't have many players that even know pot odds are a thing so it wont be taken into consideration there. I play a few home games that range from .25/.50 to 1/2 so i guess the how to use pot odds to bet question would be applied there more than my online game.

You should always (I can't think of a situation when not other than if you flop royal flush) calculate your odds.

I don't think too much about the opponents pot odds when sizing my bet. I just make sure they pay over the odds. If I have a hand it's around 3/4-1pot but I'm playing at low stakes where I will often get called down with less.

To answer your original question yes you do include their current bet when calculating pot odds. If pot is $2 and they bet $0.45 then your odds would be $0.45/($2+$0.45)*100

as Hump wrote 9 outs multiplied with 4 is 36%. But this is only valid if you don't have to put money in on the turn. Otherwise (If you and your opponent have a lot of chips behind) you have to multiply 9 outs with 2.
The pros make the river card so expensive that you don't have the odds to call.
That's the reason why pros pass if the bid is as low as 25%.
Exceptions are if you and the opponent are deep stacked so that you can win a lot of money if you hit.