Extremely solid ideas! I might not go for those enemy designs specifically, but I like the gameplay perspective behind them, especially the stealth one. A further charged version of the strong attack is currently planned (technically sort of implemented, but there's no way to obtain it outside of the debug menu) Health indication would potentially be a good idea, though I'd probably just end up with like enemy health bars to save animation time. An i-frame dash is planned as a reward upgrade for an optional boss, and while parries aren't a consistent thing on the player end, some enemies have certain attacks that can be be interrupted by a player attack to put them in a stunned state briefly (the warden already does this in 0.1, though it's not made clear, which is something that's been changed in 0.2)
What you are describing, enemy attacks that can be interrupted by a player attack, is known as clashing, with outright interrupting an enemy's attack and getting special rewards for it is known as a counter hit. It's significantly better than an I-frame dodge or parry, though a I-frame dodge, especially when balanced properly, is always going to be better than a parry.