Epever has a reputation as being a budget/value oriented but reputable and decent quality controller. I would probably choose Epever over Renogy in most situations, but I haven't seriously looked at either, so can't say for sure.
Regarding your question on the numbers, If I understand you correctly, this is not the proper way to size a controller (in full). However I believe that the controller will probably meet your needs.
You need to look on your panels and find "Open Circuit Voltage (Voc)" and "Short Circuit Current (Isc)" multiply Voc by the number of panels in series and Isc by the number of panels in parallel.
For instance if you have 4 panels with a Voc of 22V and a Isc of 6A, and your arrange them 2 series pairs in parallel (Called "2S2P"). The array Voc would be 44V and the array Isc would be 12A. Then take the Voc you calculated and multiply by 1.25x to account for extreme low temperature (44v x 1.25 =55V) (or choose a multiplier
from this chart that fits your situation)
So you would need a controller that at a minimum can handle 55V input and over 12A. Some extra margin is always good.
Then move on to the math you did above (or something roughly similar to it--taking the total wattage of your array and dividing by battery bank voltage). This can usually be exceeded a bit, especially with good quality controllers, but it means in peak conditions you may waste some watts and generate a bit of heat.
The combination of these three factors (array Voc @ min temp, array Isc, and array power / battery voltage) will determine charge controller size.
Regarding "negative ground" this is the default and you are safe to use it. For whatever reason Epever still sells 'positive ground' charge controllers so they say negative ground for their standard controllers to differentiate from their positive ground products.
If you post the number of panels and the arrangement, as well as the Voc and Isc per panel, I'm happy to help do the math if it was unclear in my example.
I'm curious about the 0.9 multiplier you used above, do you know the reasoning for that?