Unfortunately a lot of people think just because they are now use to the jerkiness and other minor issues other people should accept that....
I will say all of that is normal for this car, but for a regular non-hybrid version it is NOT normal.
Answers in BLUE
Some questions, i want to make sure if it's normal or not
1) My battery gauge never fully charged, is this common for you. There is one bar missing. Not sure if calibration error
This is normal because the car is not a plug in type, you will never get full bars unless you probably go down a long downward hill 
2) Does your car get somewhat jerky at low speed, it's like the engine is trying hard to get up to speed. It doesnt happen all the time
I believe you are referring to a creeping speed. Kind of feels like a manual transmission about to kill the engine?? I have felt that going through parking lots at a creep speed (under 5 miles w/no foot on the gas or brakes). Again this is normal for this HYBRID car, not for REGULAR automatic transmission gas version.
3) my IMA is somewhat jerky when it's cold, i feel a jerk everytime it starts. Just anoying.
Normal for this car again.
4) how long should i warm up the car before going? our temps so far ~30F
It depends. I am use to warming my cars up. Unfortunately, this is the opposite for the Hybrid. You will find that an engine block heater will be needed in cold weather if you want heat in the car while driving... I have gotten use to wearing more clothing layers in my Hybrid because it doesn't warm up fast like regular cars... An engine block heater is a module that is dealer installed with a 110v standard household plug which hangs off the front of your bumper. You plug it into your house outlet to heat the engine.
5) when i brake hard, i hear "errrr" sound, like electronic sound
Normal, sounds very Star Trekky
6) i get around 44mpg highway which is okay.
You are doing something right, I get 33mpg. But my commute is only 10-12 miles one way