According to the official SBD web site you can use low fat, lite varieties of tofu on Phase One.
As for frying as long as you are only using 1 TB per meal of the approved oils you are okay. In fact, I believe that he mentions in the book about frying your eggs and after all turkey bacon does give off some grease too. I found that by frying my eggs in 1 TB canola oil it stuck with me longer.
Actually in the book one of the testimonials is from someone who stayed on Phase One longer but I would not expect it to give you much quicker results. Again, I read somewhere else here on one of these other threads that the main objective is: health, losing weight and avoid cravings. Some of us may not be able to eat the full 3/3 carbs/fruits to be able to do that. I think if you are not jeopardizing your health I would proceed but cautiously.
If you ease into Phase Two slowly as recommended where you are only adding in one carb and one fruit the first two weeks you still are eating a very restricted carb food plan. You wouldn't be adding in 2/2 until week 3 and 4 of Phase Two.
I have never noticed any lose of energy during the whole time I was on Phase one nor did I have a headache. Maybe, that is atypical but that was my experience.