Help needed with uneven/sloped bed and nozzle dragging.

[TwinTurboGuy]

A couple months ago I completed my printer build and noticed the thickness of calibration cubes were not coming out right, front to back, left to right, etc.

After a bit of troubleshooting I discovered that the towers are perfectly vertical, but the heated bed itself is way off from level. It differs in height by probably .2mm.
It seems as if the nylon spacers, the snowflake and heated bed (or some combination of) is inconsistent. I think it's the snowflake board and to a lesser degree, the nylon spacers.
So the square does not square across the build plate when aligning. Mostly seems to be a problem with the Z tower side.

My second issue; I am getting dragging of the nozzle across the print. I've noticed my bridging is not completing and leaving hollow spots in my prints on the top surface, even with two shells.

I print in Inland Filament ABS, 85C bed, 228C hotend. Despite the first issue, I had the height calibrated perfectly on all axes + center.

Questions:
1) Is there a need to shim the build plate to make it more level? What are the best methods to resolve this?
2) Would the nozzle dragging be a result of calibrating with the bed sloped in issue 1? If not, what is causing the drag and how should I resolve?

Any help is greatly appreciated.