Hopefully someone who has used the trainer can comment on how to do so.
I downloaded and virus checked the 'Divinity 2: Flames of Vengeance v1.4.9.65-v1.4.9.70 +7 TRAINER'; hopefully it should work with DKS. There are a couple listings for cheat tables that use CheatEngine, but someone mentioned that program isn't very user friendly; the tables may make it easy to use, since you presumably wouldn't need to find the memory addresses you need to modify (or prevent from being modified). Listings for DKS that didn't require Cheat Engine were for earlier versions of the game, though they may still be compatible.
A no-DVD hack isn't going to help. The disk version of DKS doesn't use a disk check when starting the game, just when installing it; I don't know if download versions have a periodic online check.
Easy and casual are relative terms, depending on the person's skill level, character build, equipment, etc, etc.
The point of an easy setting on a game is to make it easier than the normal mode, but still be challenging enough to be fun, not to make sure nobody could possibly have problems. I've tried a couple RTS games, and did not do well, even on the lowest settings... that means I suck at RTS games, not that the easy difficulty modes were labeled fraudulently.
There are games designed to be punishingly difficult, where almost nobody would consider the easy mode actually easy.
FWIW, I played and enjoyed most of the game Psychonauts, but there was an extreme difficulty spike in the final level, which started off with an escort of an NPC using brain dead AI. I looked for cheats, but couldn't find any (did find lots of posts from people with similar problems). Finally I checked out a video of the end of the game on YouTube originally just looking for tips on what to do, but the rest of the level was all twitch based timed reactions that I had no desire to try to memorize, so I ended up not finishing the game (it was still an excellent game, otherwise). There were a few frustratingly difficult sections early in the game, but I was able to do them after going through a few times, or tweaking how I had my gamepad options setup.