1.I have used 50W HID before, and they are just too bright, and might be dangerously blinding others.
2.It wont fry your electrics as the hid kit will come with its own ballasts. Note your std halogens are 55W anyway, so 50W actually consumes less power.
3. If you use 4300K they wont pull you over
4. I agree with jamchen, 35W is bright enough in Australia. Also the extra heat produced by the bulbs might cause it to overheat. At least thats what happened to my other car (yaris) , the reflectors have some white blemishes due to overheating.