How are the three marks of existence experienced through Samadhi meditation? Could dry vipassana &amp; pure one-pointed samadhi type meditations just be different approaches to the same enlightenment?

If one attains the fourth jhana with one pointed concentration does one experience anatta? What about anicca &amp; dukkha? How is sunyata related to anatta?

Is it really necessary to focus on non-consepts at some point in order for one pointed 
(ekaggata) concentration to lead to enlightenment? 

Are there scriptures that can help us understand this?
The question is loaded with erroneous doctrines that epitomise this other question.


There is no such thing as "dry vipassana". Since the suttas (SN 22.59) say vipassana results in dispassion &amp; nirodha, obviously any vipassana-dispassion-nirodha will contribute to calmness &amp; samadhi.
Vipassana means 'clear seeing'. Since 'vipassana' is 'seeing', it is 'non-conceptual'. When the Burmese teach the practise of "mental noting", such mental noting is not vipassana. Instead, it is a crude form of 'sampajjana'. 
Samadhi means the mind is not distracted; which is the meaning of 'one-pointedness'. 'One-pointedness' does not mean have narrow awareness upon a tiny object or point. 
Vipassana is a result or fruit of samadhi (AN 4.41; AN 11.2; MN 149). Samadhi &amp; vipassana are not "two different approaches". 
When the mind is not distracted, it naturally automatically knows the breathing. 
When the mind naturally knows the breathing, it also naturally automatically experiences the breathing is impermanent and also experiences the body breathes rather than the self breathes. Seeing this not-self of the breathing is what the suttas mean by "alien". This is the beginning of vipassana. 
"Dukkha" in relation to impermanence has a different meaning to "dukkha" as a noble truth. In relationship to impermanence, "dukkha" means "unsatisfactoriness", i.e., the incapacity of an impermanent thing to bring lasting reliable happiness.
Suttas about how vipassana is a result of samadhi include AN 4.41, AN 11.2 and MN 149.
In summary, the Buddha taught one path (Noble Eightfold Path) which culminates in samadhi and has two fruits (samatha &amp; vipassana) that occur in tandem.



  Having thus developed the noble eightfold path... for him these two qualities occur in tandem: tranquillity &amp; insight.
  
  MN 149