Advice on aero wheels
Except for the steepest of hill climbs, aero wheels will almost always improve speed; however, the choice among race wheels will depend on the types of races you do, your strengths as a racer, how important small improvements in aerodynamic drag are to your goals, and the size of your bank account. For short individual time trials, .0025 m^2 savings in CdA (roughly, one-sixth the size of the difference between a very aerodynamic front trispoke wheel and a "standard" box rim) is worth 10 seconds in 40km and can mean the difference between standing on a podium or grinding your teeth on the long drive home. For citizen-level crit races where crashes are common, you may not want to risk expensive wheels unless your riding style is so dominant that you spend the entire race off the front and turn the crit into an ITT. For a long TTT like the Styrkeproven, aero wheels certainly won't hurt but the benefit of a deep set of rims may not be worth the cost if your team time is determined by the 10th rider to cross the line (in fact, in that case, a cheaper and potentially more effective strategy is to have everyone of the team use tight clothing and low rolling resistance tubes and tires). 

Purely from an aerodynamic drag point of view, several of the larger wheel manufacturers (such as Zipp or Hed) provide information on aerodynamic drag differences (in grams of drag "force") between their various models and standard box rims. Most of these differences in grams "force" are measured at either 30 mph or 50 km/h. You'll want to convert this to the average speed you expect to maintain in your various types of races (the aero drag varies with the square of air speed) to make a rough estimate of the benefit you'll reap from switching to better rims. Exact calculations will depend on yaw angle but a handy rule of thumb is that a savings of 50 g of drag "force" at 40 km/h is roughly equivalent to a savings of 0.5 seconds/km at the same power output. Thus, the difference between a box rim and a trispoke front wheel could be around 1.5 sec/km, or about 1 minute in a 40km ITT.