HID kit Questions. Advice needed
 

I own a 2008 volvo c30 t5 and I'm considering buying a HID kit for my stock housings. I've been told that having projectors with HIDs is the way to go but my worries are:

1.should I go 35w or 55w.

2.what brands are good that won't break the bank.

3.will they go bad is they run all the time as my default running lights.

4.will they melt my original stock housings.

5.will they cause the car's computer to spit out error codes.

Those are the main questions.