#3 Searching. Never found a searching key. Didn't know about vines until 2/3 through because they would have highlighted in a search. I like to have to search for traps and treasure and hidden objects.
I agree with a good chunk of what you suggested but this one in particular I HATE. I find it hard to go back and replay BG and many of the other isometrics of old for the sole reason that traps and detecting them in this manner (with no passive perception) has one of two net outcomes for the player:
1) The player constantly has one person in perception mode leading the front of the party looking for traps and secret stashes, massively slowing down the entire game for no real reason.
2) The player saves often never knowing when the next super deadly trap they don't have time to hunt for is going to show up and ruin their day. They miss tons of treasure of which they had no indication was there. Forget to save for a while? Have fun replaying the last hour or two of the game trying to get back to where you were again.
If that doesn't sound like good gameplay, that's because it isn't. It's the game arbitrarily slapping you on the wrist because you have not played the game before or have forgotten where all the traps/loot were since you last played. Pillars of Eternity also did the same thing and it's the main reason why I have never finished playing it because I can't stand missing stuff but making sure requires me to comb every zone at slower than a snails pace.
Most of us know and love the old isometric gems of the past, but let's not copy their worst aspects into modern gaming please.
[Edit]
There are two ways I can think of that a similar system could be implemented that would not be an active detractor from gameplay:
1) Make it simple a stat that determines whether or not you see things without active intervention. (like passive perception)
2) Make it so that it will point out things that could otherwise be seen an interacted with but are not obvious.
The stat one would not be hard to do, but the second one would take a lot of clever level design.