The PCB vendor will usually want a minimum of 1=via_diamater/layer_thickness to get good plating of the via walls.
0.010" is usually the smallest diameter via you can get with conventional drilling. Smaller than 0.010" requires laser drilling.
The equivalent circuit model in your simulator will also have limits on W/H.
You can probably get away with an edge-to-edge spacing of 1 to 2 diameters but they must be staggered to prevent fault lines.
There are papers that show the resonance of via-fences; maybe look those up. However ideally you want them close as possible.
Your PCB vendor will have the final say with design rules.