Class feats are an optional part of a class. They are designed to reward skill development with unique bonuses. The amount of the reward is based on the feat level you buy. The more levels you have in a feat the bigger the bonus you will receive.
So you do not become confused, pay attention too the terms "Skill Level" and "Skill Points". Skill levels are bought with skill points. The skill points are earned each time you gain a new level. The amount of skill points you gain is set when the class is made. So skill points can be used to pay for skill levels or class feats that are not restricted.
Before you can buy any level of a feat you must have the required prerequisite skills and skill levels. Once you obtain these you will have one or more feats available to buy.
Feats are paid for with skill points and cost one of two values of either related feats or open feats. A related feat is one that bought when a class is designed and will cost less skill points to buy when you have the points to do so. The second cost is for the open feats and these are feats that are not directly related to your class but are not restricted either. An open feat will cost more in skill points. Each level you buy also has a level cost too. The level cost is multiplied by the level you wish to buy and is added to either the related cost or the open cost.
As a related skill of a level one of Arcane Battery you will need 21 (15+(6*1)) skill points and must have 20 levels of skill in Arcana. At level 2 of Arcane battery you will need 27 (15+(6*2)) skill points and must already have 40 skill levels of Arcana. The expense increases from here on out.
The first level of improved jump as an open skill will cost 12 (10+(2*1)) skill points and requires 10 skill levels in jump, yes this feat feeds back into its own skill. Level 2 of improved jump will cost 14 (10+(2*2)) skill points and it will require 20 skill levels in jump.
While the feats can sound expensive keep in mind Red Ash has a multi-tiered skill system. So going from a jump skill level of 10 to 20 is not 20 skill points. Read more in skills to understand the mechanics involved in skill progression.