(Beginner) How do i achieve these results? I am just getting started on trying to create a custom asset library for future use in projects, i am able to make pretty much any basic object in blender however when it comes to exporting and texturing my model i run into strange issues related to my mesh. 

The Workflow i think i am trying to use is: Making a Low/High Poly model in Blender, Exporting to substance to bake ALL my maps apart from an ID map what i do in Blender, and then exporting my results ready to be plugged into whatever engine i decide to use. 

So first things first here is the reference image i am using 

Next is my Low Poly model.  
In order to make my high poly model i used a Bevel modifier in combination with a subsurface modifier, this gave me the crisp edges look i was looking for. 

So my first question is is this the best way to achieve this or should i alternatively have sub-surfed and then manually constrain the edges with edge loops? 

After making my ID map in Blender (Simple enough) i export my fully UV'd Low and high poly to substance painter where i begin to bake out my maps. This is where problems start to arise. 

My textures on my edges look terrible  

And is most likely due to my normal maps looking like this (Baked inside Substance painter)  

I know my UV dosnt best utilise the space in the grid etc etc however both the High and low are operating from the same UV from the same coordinates, if thats the case why am i getting such awful results, is this a Mesh/UV problem i am causing from within Blender, or is it something in the Baking and texturing process in Substance painter? 

Any help appreciated.
This is due to the resolution of your normal map. You can improve the result by creating a bevel in your low poly mesh, and by merging your maps to optimize your texture space.
This will give give you a smooth effect.

You can achieve a hard border effect without bevel, and with both hard edges and separated UVs.

Also, you can increase the dilation width to avoid some pixelated border effects.