I'm not the developer, but on the alpha 0.3 development post it says that the escape has a "4% * (current level)" chance to succeed. So it becomes more likely for you to escape the higher level your furries are, but yeah, at lower levels it is not very useful
The difference between just money/XP rewards and boosts, is that boosts provide you an additional amount of XP/money from winning battles, up to twice the normal reward. As an example, if you have a 30 XP boost ready, if you defeat an enemy which would normally give you 25 XP, you will now receive an additional 25 XP from a boost, for a total of 50 XP. This will then leave you with a remainder of a 5 XP boost to be granted in the next encounter, so if you were to defeat the same enemy again, you would now get a 25 base XP reward with an extra 5 XP bonus for a total of 30 XP. Same rules apply for gold boosts. Hope that explanation makes sense to you.