You really need to find out how many kW you have to play with, other people are going to be using the grid too. To get you started, a 2x6990 rig should be around 1kW.
1kw a month? their are 12 units in my complex (building b) and dozens of buildings i dont know how many would be on the same grid.
No, 1kW/hour. But, if that quote is directly from your landlord's website, and since a kilowatt is a constant rate, and if it only says 30kW rather than 30kW/month, you should be fine with one or two 2x6990 rigs.