I used to have my hair highlighted all the time. I assume you mean you are doing this at home. You might consider calling a salon for their advice. It couldn't hurt. Have you dyed your hair at all since last year? Even a touch up? You're right about the orange part. The bleach over black dye will do that. It's likely that dying your hair blonde over and over will not work and the ammonia will damage your hair more. You need the bleach to strip the black out. I would do exactly what you are doing. Bleach it and let it get pretty white and then use a toner. Then do the blonde dye. I'm no professional, but that's what I would do. I dyed my hair black last year and then in the summer I went back to brown with bleached highlights. The bleach took care of the black. I think you should try a small piece first that way there will be no emergency visits to the salon

There is going to be damage because that’s what bleach does. I’d use a leave in conditioning treatment. I even leave a little regular conditioner in my hair from time to time, but it might sweat the color out. Hope that helped a little