Hi,
You will find all the necessary BASIC details about HID lamps here, its a nice read and a must in my opinion before you decide to put in HID lamps-
HIDRetrofits | A High Performance HID Projector Retrofit Headlights Resource
I used this information to decide on the HID unit I wanted. Projector lens I chose was recommended by the guy who installed the unit in my car. I decided on putting in Osram HID unit (35 W/ 4300 kelvin - this is more than enough!) and fitted those with AES projector lens (Chinese, but reliable). The HID unit (bulbs, ballast and relay) was 9k in price and projector lens was 3k in price.
As long as the cap at the back of headlamp unit is cut and sealed properly and ballast/relay is housed well there are no issues fitting in HID in your I10.
I would strongly recommend projector lens as they help focus the light and avoid light spread as also explained in the link. I had first fitted in HID lamps with stock reflectors. Soon I found myself unhappy with the light spread and then wisely decided to go in for projector lens.
When you approach a mechanic with this information in hand he would know you are an informed guy and he would not make shortcuts
Also, my HID lamps were fitted without opening up the bumper of the vehicle, I had previously seen mechanics open up the bumper of the car to fit in HID's.
Cheers,
Sunit