Is the Yaka Arrow able to penetrate Iron Man's suit in Avengers: Endgame?
Unclear although I would lean towards yes... though that depends on the plot of course.
The Yaka Arrow is routinely shown to easily pierce various enemies including armoured ones and can even pierce the Necrocraft of the Kree and the Kree in their armour pretty easily without slowing down. See the clip from Guardians of the Galaxy on YouTube here.
It is even able to pierce various metals and objects inside of the Ravagers ship and blow up the fuel tanks without getting destroyed in Guardians of the Galaxy Volume 2, see here.
However, it does get destroyed quite easily against Ego in Guardians of the Galaxy Volume 2 when it is just hit into the floor against something it was previously doing well destroying. This calls into question how strong the Yaka Arrow actually is. See the scene here. Although when getting destroyed here Ego hits it on it's side which "cuts" it in two and arrows aren't known for the strength perpendicular to themselves.
As such it is shown to be inconsistently strong so we can't assume how powerful it is, especially when going up against the Iron Man armours which are made out of strong alloys.
I believe so, yes.
The Yaka Arrow could pierce through the Kree NecroCraft AND kill its occupant. That thing is built for space combat, so would be pretty well built.
And so far that we see, Yondu has no limits on the amount of momentum he can get that arrow to generate. It could very well damage the Iron Man suit purely as a kinetic weapon.
It depends on the user. The arrow is constructed from Yaka metal which is a 'sound reactive' material. Centaurians are able to control the behaviour and concievably the composition of the arrow through whistles. It is known that different users are able to achieve varying levels of skill with the arrow allowing them variable control over the velocity of the arrow. If that concept is followed to the extreme it should be theoretically possible for the arrow to pierce any object or substance provided that the user could manipulate it to a high enough velocity, though the survival of the arrow may be in question at that point.