I have to disagree with you on almost every point and I've been playing on tactician difficulty.

1. Enemies will typically only attempt pushes or shoves on you if you perch yourself on a ledge, I've never seen one go out of there way to shove me to death. I have cheesed a few fights with pushing Enemies to their deaths mostly because they fucked up and gave me too good to be true opportunities, but I largely just don't even use the shove mechanic.

2. Endless ambushes? Are you just running full speed around the map? Are you taking your time? Other than a few scripted encounters, I can't recall a time I've been Ambushed, usually you can see every enemy on the horizon long before they spot you and set up optimal positions or practically choose your battleground.
I've maybe only had to load twice in my whole playthrough due to unexpected mechanics or severe tactical mistakes I've made.

3. This point just sounds like total bait. Have you ever played D&D? You don't get xp by killing anything and everyone you meet. This might explain why you are having such a hard time with this game. Almost every encounter has an innumerable ways in which you can use social skills to gain the upper hand that don't involve the enemies killing themselves if you take the time to talk or come up with a plan. Even on an evil playthrough there's a difference between chaotic evil and chaotic stupid.

4. Pay attention to your enemies, they frequently make mistakes. Especially when it comes to positioning. Sometimes they walk into an oil puddle. Sometimes they climb onto a destructible object to gain the highground, sometimes they walk or stand under things on the ceiling you can shoot that fall onto them. Sometimes they are standing on the edge. The enemies make tons of mistakes when it comes to positioning Especially when they become overzealous attempting to reach a weaker party member. Enemies can also be quite predictable making them incredibly easy to funnel into perfect positions or groupings to cast AOE spells on.

I think you need to take it slower and rethink your mindset, or just play on story mode if you want to wipe the floor with everything and know you are going to "win" everything.