What are the most important numbers? The last set. These will tell you how much money's worth of performace will the village boosts add to the tower, or in simplified form, you'd have to spend this much on more of similar tower to get the same performance.
Example: Judging when to upgrade a village to 2/1, with optimally placed 3/0 tack shooter - the value of 2/1 village more than doubles the tack shooter's performance (double damage AND higher speed) - it's worth spending about 1700 in more tacks. So, if you have a village with 1 tack shooter underneath it, it is still cheaper to add another tack (about 1250 with village discount), but once you have two, it is better to then upgrade the village to 2/1 - the cost of 2900 is lower than performance boost for the two tacks (worth about 3400).