Subject to your particular rules (or exam protocols) and SOPs, the aim is to be conservative and cover all bases so that any surprises are reserved for the bar on the overnight rather than the aerodrome arrival ...
Hence, the usual approach is to look to nil wind on the most suitable runway unless the forecast may result in an excessive crosswind. In that case one would check for the lesser RLW of the nil wind case and an into wind runway with a headwind equivalent to that maximum crosswind.
Although I've not seen it done so, a similar approach might be adopted were the forecast to provide an excessive tailwind on the preferred runway .. again, in an effort to cover the all bases consideration.
As to slope, the preferred runway chosen for the calculation will cause whatever slope exists to be considered. The AFM should have slope and factored wind correction grids included.
TOD calculations are not the problem - if you guessed wrong or the forecast turns out to be non-conservative, you offload fuel or payload or wait for more suitable conditions. The significance about the landing calculation is that you will be in flight and don't have the opportunity of waiting around all day or, in many cases, diverting to a variety of alternates ergo you need to have a plan figured out in advance.