Due to some problems occur to my headlight, so i was suggested to replace the whole kit of my HID. (including the Ballast)

And here is my question, which one should i buy D2S or H7?
Moreover, i think i break my housing when i first time install my aftermarkte HID.

Do i need any special tools to install the HID again?

And i am going to the HID fog too, so besdies H11 HID are needed, anything else?

And where do you guys usually buy HID?

Any help will be appreciated