How exactly do multiple attacks interact with an off-hand attack? Does the off-hand attack count towards the total number of attacks, or is its penalty self-contained?

Example: I have a character with Attack 220 with a Longsword and a Shortsword. I can make up to three attacks with the Longsword, and the Longsword is Medium, so under the new rules, it's -30 for each attack after the first. I don't have Ambidextrous, so my Shortsword attack has the normal -40.

If I were to use the Attack action to make three attacks with the Longsword, then all three attacks would be at 160.

If I throw in a Shortsword attack, does it become a fourth attack? 220 minus (3 x -30 = -90) equals 130, so do I make the three Longsword attacks at 130 and the Shortsword attack at 90 (Note: I have another question below, and I use this as a starting assumption, but only because I need some way to frame the question.)

Is the Shortsword attack independent? Do I make three Longsword attacks at 160 just like before, and then the Shortsword is at 180 (220 - 40)?

Is it semi-independent? Ex: Only the Longsword attacks determine how many attacks are counted, but the penalty goes to all. Three Longsword attacks at 160, and the Shortsword at 120?

How does it all combine?

...

Next question: how does this combine with any Counterattacks I might have opportunity to make?

Let's say I declare my intent to attack three times with my Longsword and once with my Shortsword (and, like above, my Attack ability is 220 and I lack Ambidextrous).

Before my turn comes up, I have two opportunities to Counterattack with my Longsword (and let's say that in each case, I ended up getting a Counterattack bonus of +30).

Do I calculate the attacks before my turn even begins (Example 1), or only when my turn comes up (Example 2)? (I'm using my first assumption from above for this. Obviously, if my second or third guess was how it's supposed to work, then assume I'm using that as my example instead.)

Example 1: 1st Counterattack (130 + 30) = 160, 2nd Counterattack (130 + 30) = 160, my turn 1st/3rd Longsword attack 130, Shortsword attack 90

Example 2: 1st Counterattack (220 + 30) = 250, 2nd Counterattack (220 + 30) = 250, my turn Longsword attack (which would have been one of four total attacks had the Counterattacks not happened, but instead is only one of two during my turn) 220 - ?, Shortsword attack 220 - 40 - ?

Example 2 also raises the question of how the new rules deal with multiple sizes of weapons. Do I treat the one Longsword attack and one Shortsword attack I get during my turn as - 20 for the Small size Shortsword or as - 30 for the Medium size Longsword? Do I only apply the penalty that applies to the weapon (- 20 for the Shortsword and - 30 for the Longsword)?

How does it all fit together? And I apologize if I'm not explaining this well enough.

My understanding is that the offhand is semi-independent, so first three at 160, offhand at 120.

Counters are done immediately, so 160+30, 160+30, then first 160, and 120. You still swung the same number of times, so the only variable would be the counterattack bonus.

I'm not 100% familiar with the new rules, but I assume it's similar to the rule of "always use the speed of the slower weapon" so both would be -30. If I understand the math, it's the same concept.

the secondary weapon give you an extra "free" attack with an integrated penalty(-40 or -10) meaning that you don't get a general penalty out of it. It is as silkentoes said : 160 for the 3 longsword attack and 120 for the shortsword one.

When it comes to counter attack and attack : with 220 you can potentially do 3 attack however at the start of your turn you must declare how many attack you wish to do before rolling anything and if you get a counter attack you need to declare how many you intend to do on your turn. Because the malus apply on every single one of your attacks be it a counter, a normal one, and off-hand one or a whatever limb power you got. This is your intention that determine the malus coming from multiple attacks not how many attack were already done.