Energy is still used for opening danger rooms and treasure rooms. You can also use it to buy orbs of alchemy. In fact, if you didn't find any orbs through missions or adventuring, then crafting would cost exactly as much energy as it used to.

You get a bunch of Sparks of Life from missions. You also find them occasionally in the Clockworks. Whether you spend them faster than you earn them depends on how often you revive. I am certainly accumulating them.

I'll let someone else advise you on battle sprites for bombers.

We don't know how long you've been away, so we don't know what balancing has been done since you've been gone. Consider reading the release notes on the wiki or in the Announcements forum. DA has not overpowered relative to the other elemental swords for at least a year. Last summer, damage numbers on guns and bombs were buffed about 15%.

You can buy orbs of alchemy with energy, or find them in the Clockworks. You should also have some from missions. Consider reading the wiki.

To find out what's new, read the release notes. It will give you a more reliable and thorough account of changes, than any forum thread will.