Hey guys,
I encounter two issues during my sittings and will be happy to get some help from you.


Even if I manage to stay focused on breath, I feel in the background the will to do this, which feels like an effort which summons part of my attention in a discrete way. The result is that I tend to deploy some of my attention on breath to the other mental entity and therefore am not thoroughly focused on my chosen object.
I suppose this is the symptom of some wrong approach, so please let me know what is the problem and if there is some solution for it.

Also, during my concentration practice, I feel there are two distinct qualities of "thinking about nothing". There is a very absorbed one, which puts me in a state of pleasant stillness, just like when I am quite attentive to some topic, but there also is another way of having an empty mind, which is fuzzy and confuse. I don't have thoughts but I have a kind of dumb nothingness, like the moment when you are asked some difficult question and the mind doesn't even know what to begin with in sorting it out.

I would be careful with this one. Concentration requires effort. You want to see effort in practice? Just let your mind wander from object to object and notice a subtle "like or dislike" impulse with each movement of your attention span. Your limbic system is constantly active looking for dangers and opportunities, even in meditation, so what's the solution? You have to practice concentration so you get good at it. The intention to pay attention is just another intention. Any movement to "want to get something" will have a slight worry that it won't get it. This is true even in meditation attainments. Practice makes the wiring more reliable.

Try to concentrate for its own sake without any guarantee of success and the worry will drop further. If you get absorbed, great! If you don't, great! Preferences cause stress so meditating without a neediness for one state over another is a big insight.

that "will to concentrate" is the centerpoint what is untangled at MCTB 4th path.

you can't untangle it directly, there is certain things done first.

1. perception change. That will cut the cord between your centerpoint and the eye perception. Thats not yet centerpoint untangling.

2. Once the perception change is done the essence of your mediation will melt and falls pass heart and you then can meditate from the "inside", but yet can't untanlge the centerpoint. You will help the essence from the inside back up to the head again. There where somewhere in the middle possible that you will experience dark night.

3. void. you need to see the void. But there is a few events before that. one is unknown moment, and then there is a snapping event.
After the void event you approx also know what to do for untangling the centerpoint, and the most importantly are now able to untangle the centerpoint.
void is accessed from the perception(eyes). Once you see the void you still will have to do two things to untagle the centerpoint, your essence will need to reach from bottom to the center with the help of the eyes again.

But its easier because the things you do you can also know innerly without reading it somewhere. And there is more things happening, but are not witnessed clearly, because they are subtle.

When a loud noise occurs, it is not required to make any effort to hear the noise. The hearing is automatic due to the nature of auditory consciousness & the auditory sense organ. A smell is the same. A sight is the same. The touch on the skin, for example, by a mosquito, is also the same. No effort is required to sense a touch on the skin. 

Awareness of the breathing in & out is the same. No effort is actually required to sense the breathing. Particularly, no effort is required to 'focus' or 'direct' attention onto the breathing. The same as a sound, sight or smell, if the mind is quiet enough, awareness of the breathing will occur automatically because, when the mind is gentle & silent, the breathing in & out becomes the coarsest or grossest sense object (similar to a very loud noise).

You are correct when you say: "the will...summons part of my attention". 'The will' is actually a thought; although more subtle, the same as any distracting thought. For the purposes of lucid sensitive discerning samadhi, the will as a thought is also a hindrance to deep samadhi. 
 
As for 'dumb nothingness', this sounds simply like a part of the mind that remains unclear, which is completely normal. The path is a gradual process of purifying or polishing the mind so naturally, even at lower levels of genuine samadhi, the mind will have 'foggy' parts, despite being concentrated. 

So to get rid of the will to concentrate, I suggest trying to get rid of the intention to observe the breathing.

Keep in mind, the path of the Buddha is not the path of watching breathing, per se. 'Anapansati' does not mean 'mindfulness of breathing'. 'Anapanasati' means 'mindfulness with breathing'. The path of the Buddha is abandoning craving and, when the mind keeps itself in a state free from craving, that is 'right mindfulness'. 

Kind regards