Ahh yes, the ultimate go to move. Nothing beats it 
Just remember that there are a FEW EX moves in the game that are actually worse than the normal version.
Example: Hondaâs EX Oicho throw.
You spend a bar to get:
The range of jab.
The damage of medium
The startup of heavy.
No extra throw or hit invulnerability.
Not sure what Capcom was thinking when they programmed that move, but I always hear honda players make fun of it.
Pretty sure Sim has a few arguably weak ass EX moves too.
You can do a Tatsumaki off it in corner, You can also go:
EX palm up > EX -slightly charge- Hadouken > Ultra shakes fist when it gets done to me by my other half ^_^"
It makes for easy ultra setup in corners.
Away from corner you can go into another just normal palm.
As for other ones. I find Bison doing EX Devil reverse (on the starting part, not the second bit), can take him up very quick on wakeup which can pull him out of some situations like Wake-up > throw attempts.
Vegaâs EX FBA is handy for hitting into an Izuna drop, but it is very easy punished.
His EX Scarlet terror can juggle off a light one. so you can go Light Scarlet Terror > EX scarlet (You hit with one hit only on the EX but it does extra damage).
His EX Sky High Claw goes through projectiles but attempted at full screen is dangerous because itâs piss easy to counter.
On Guile he doesnât have much use out of his EXs unless youâre going for Guile-High kick (His roundhouse) into EX flashkick. On an EX boom itâs okay because itâs quick but comboing it is better.
Chun Liâs Wake-up EX Spinning birdkick is quick and ouch-worthy.
Other than that, Keres covered your key points.