Is placing vias on GND center pads the same as adding drill holes array for the pads? I already have vias placed on existing footprints and there are DRC errors as a result of placing these vias directly on the GND pads.
Is there an easy way to just delete the DRC errors for these? If so, how do I do this? Or is it still highly suggested I create the GND pad with an array of drill holes?
You can define the thermal pad as a surfacemount pad and add vias to it as you have done. The DRC markers are a result of the Route Keepout shape that you have defined around this thermal pad.
To correct this issue, select Edit > Object Properties and select the Route Keepout/Top shape. Add the property VIAS_ALLOWED.
This allows you to add vias without getting the DRC markers.