Merch on the side to offset the cost, I'm still iffy on long term use (just using set from daily spin atm) since to me it's like warbands and I don't do those either since it's a free hand me out not even related to the skill.
Less than 25%.. Energy increases the exp per memory by 25%, but gathering the memories remains unchanged, and is about 19k of the hourly exp. So roughly 80k instead of 95k