The map marker does not work

From what I can gather, the relics only put points towards the dots and when you complete the story and the relics and purchase every skill, then it completes it. As you progress through the story, it unlocks the wave like thing at the bottom above the larger 2 sharks, spider and heron. Then, later the story unlocks the tree and the vines beside it. and the mask demon in the middle. I beat the game and only thing I have yet to unlock is the 2 wings at the top and all the dots that trail up to it. Which means I need all the relics to get the wings up top.

Edit: The blue you circled is in fact, from the main story. also right above the middle with the 2 faces is a tree, the tree is from another main story quest. All the rest which you labeled in red and yellow are from skill unlocks that you buy with skill points. when you spend points in spider, it goes towards spider art work etc. The relics only give those dots that you circled in green. I believe that when you get all the relics/ collectibles that you get the 2 final "wings" up top, As you can see, each dot represents 1 relic. Everything else is via main story/ spent skill points towards the animal type. basically that means each line of dots that lead up to the top Shark picture on each side equals 60 relics. since there are 120 relics in all and 2 sides. The memory cards may also play part in the tattoo. Maybe part of the line up top above the wings.

edit #2. Relics only unlock the dots and the wings at the VERY top above the heron's. I know this because I -maybe- collected 5 relics before I beat the game and everything was colored in besides the dots and the 2 wings up top. Right now I am sitting at 24 and the dots, which I counted are 24, is right above the head of the seagull looking icon just above the wave that you highlighted in blue. Now, you do of course get XP from the relics and you might've spent points before looking at it again and thought that, but I was too lazy to get the relics and focused mainly on the story. I could probably show you a picture? Since you have more relics than I do you can see the difference.

I personally love the Bow and Arrow approach of Far Cry 3, although I find it to be completely overpowered (OP).

The quick answer to all of your questions, so as not to bury my answer in a wall of text:

Will arrows fly further or deal more damage if the Recurve Bow is drawn longer (similar to Skyrim)?

yes to distance, no to damage.

Do arrows always hit the center or a specific point of the crosshair/sight or is its accuracy affected by the bow's draw length?

Accuracy is affected by draw length to a small degree.

Now, to explain in depth my answer to your questions.

Will arrows fly further or deal more damage if the Recurve Bow is drawn longer (similar to Skyrim)?

There are 3 different types of arrows that I have come across so far: Normal, Fire and Explosive.

Normal and Fire arrows, when draw to full length will cross the same amount of distance. Explosive arrows cover a further distance for some reason, I have come to terms with it being a bug.

No matter how far you draw your bow to shoot Normal or Fire arrows, they will kill a person in one hit. Even if you hit them in the foot, the one exception being Heavy Armored Pirates. I know this to be true as at point blank I can quickly draw and fire and arrow, then watch annoyed with the OPness of this act as they die. Fire arrows having the added benefit of possibly causing a large wildfire and catching any of your targets buddies on fire as well. Although note, it seems to affect animals completely different, almost like the developers had intended the Bow and Arrow to be balanced but for some reason its only balanced when hunting. As you may have already noticed that the bigger animals will usually take more then one hit even when struck in the head or chest. Explosive arrows kill anything near the explosion in one hit, besides Heavy armored Pirates.

Do arrows always hit the center or a specific point of the crosshair/sight or is its accuracy affected by the bow's draw length?

I have found this hard to judge as there is a pretty realistic weapon sway present in Far Cry 3. Weapon sway being the figure 8 your sights will created caused by the artificial breathing your character does. The accuracy present in Far Cry 3 is only present when "firing from the hip". As when aiming down your sites you will hit your target "60% of the time everytime", no but seriously you will hit your target everytime when aiming down your sights. Unlike FPS RPG games such as Borderlands where accuracy is the percent chance your bullet will be straight and true.

Although, they have made arrows affected by distance by adding a somewhat realistic drop. So for example, when firing at a target 25 meters away you wont experience much drop if any. A target 50 meters away however you will have to adjust your sights properly to account for the drop. Of course this all takes some practice, and for some reason Explosive arrows go further then Normal arrows.