Is Dynamesh needed for 3D printing( excluding decimation master )? Also is the 3D prints quality affected by whether dynameshed or not?
Nope and nope.
theoretically yes… 
it can be useful in situations when you prepare object for printing that is constructed from couple of subtools where every of them is as separate object. Dynameshing it you make on whole watertight mesh that can solve some problems in printing.
and looking how much Cryrid is experienced I wouldn’t go arguing with him 
Here’s what I’m getting at.
Is Dynamesh needed for 3D printing?
Dynamesh is not needed for 3d printing. It has nothing to do with 3d printing since it is a basemesh creation tool designed to create an even distribution of polygons for sculpting. We were printing 3d models long before Dynamesh was a thing, and we can print out models from other 3d programs without ever running the file through zbrush / dynamesh.
There may be instances where dynamesh could help - perhaps you have a finicky printer and a model that has no business being printed - but even then there are other tools and methods that can accomplish the same tasks required to fix the model. Even if dynamesh is useful 10% of the time, it’s still not needed 100% of the time.
Also is the 3D prints quality affected by whether dynameshed or not?
If you can’t tell by looking at a model’s surface if it is the result of box modeling, dynamesh, zremesher, remesh all, manual retopology, live booleans, sculptris pro, parametric sliders or a decimation algorithm, then you’re not going to be able to tell on the print. What the polygons are currently doing matter more than how they came to be. This is why decimation master is so awesome as a final step; it is a lot easier to transfer and/or process a file for printing that has been decimated to a few MB than one that is closer to a GB because of an unnecessarily consistent polygon density.
Here’s the caveat to this: the quality of a print isn’t affected by whether a model has been dynameshed or not, but if you DO happen to dynamesh the model then the quality of the print can be affected by the quality of the dynamesh. If dynamesh turns a crisp edge into a jagged mess, starts noticeably webbing protrusions together, closes cavities, or creates numerous holes, then these are things with the potential to impact the quality of the print. Your specific dynamesh settings can also impact whether the mesh is hollow or not, in case that matters to the printing method you’re using. But if the only discernible difference is the number of polygons, then there is no discernible difference on the quality.
Thank you very much guys.