Hi, i'll try to answer all of your queries
1) For the front grill, you will not have to change the complete bumper, only the grill part is removed
2) DO NOT install Hid's even if you get them for free, trust me they are just a waste of money, they have ZERO visibility plus you will be irritating the oncoming traffic all the time, get Osram NightBreakers H4 Bulbs or stick with the OEM ones.
3) You will have to replace the rear screen, no loss of value. Keep the original one with you if you want. I exchanged mine with the defogger one with a difference of Rs. 1000/- Do not get the rear windshield tinted or the defogger will stop working pretty soon.
4) EPS was the most lovely part of the car. I kept my car for 3 years after installing EPS, and never faced any issue regarding stability, drive or whatsoever, just get the EPS calibrated correctly (Zero Point Adjustment).
Feel free to PM me incase of any further query.