Levelling
Each skill has a level that start at 1. Level 1 starts at 0 XP, and each level requires more XP than the last. Here's how much XP you need for each level, up to level 100 which is the max level.
[0, 84, 174, 270, 374, 486, 606, 734, 872, 1021, 1179, 1350, 1532, 1728, 1938, 2163, 2404, 2662, 2939, 3236, 3553, 3894, 4258, 4649, 5067, 5515, 5995, 6510, 7060, 7650, 8282, 8959, 9685, 10461, 11294, 12185, 13140, 14162, 15258, 16432, 17689, 19036, 20479, 22025, 23681, 25456, 27357, 29393, 31575, 33913, 36418, 39102, 41977, 45058, 48359, 51896, 55686, 59747, 64098, 68761, 73757, 79110, 84847, 90995, 97582, 104641, 112206, 120312, 128998, 138307, 148283, 158973, 170430, 182707, 195864, 209963, 225074, 241267, 258621, 277219, 297150, 318511, 341403, 365936, 392228, 420406, 450605, 482969, 517654, 554828, 594667, 637364, 683124, 732166, 784726, 841057, 901428, 966131, 1035476, 1109796]
The Hero total level is the sum of all skill levels, meaning the Hero will start at a level corresponding to the number of skills (plus bonus). The Hero also has total XP which is just a combination of all skill XP, but that number CAN'T be used to calculate the total level using this formula.