hi, for every antibody have its own antibody solution so u can use the own diluter not u prepared it 

You can use %BSA+%serum of the source where  the Ab-II is made and I would not use triton during Ab-I incubation since it is a detergent and could affect the binding between Ab-I and epitope

I agree I suggest removing the Triton X-100, but if you are not reusing the antibody there is no need even to add azide as you normaly incubate at 4C and it is not enought time for anitoboy solution to become bad due bacterial growth. Actually if the proper blocking have been performed even PBS works quite ok for dillution of antibody.