Altered top tilt channel balance

I have a 795 with a hook at the top, instead of a screw.
My concern with using the screws is determining what kind of screw to use and if using the screw plug and screw will in any way affect the window function. These are tilt single hung windows and I just want to make sure that all functionality remains.
So I guess my questions are:

1. What type of screw and is this something you would provide?
2. can you provide the screw plug also?
3. The online pictures seem to indicate that the balance comes with the T-lock shoe ? is this a correct assumption or is it separate?

So for the other option of a custom balance I am interested in a price quote. I am wanting to order at least a dozen of these balances and if there are 2 to a window then that will take care of 6 windows. For the custom ordered balances will they include the T-lock shoe as well?

I want to discuss all this with my husband as well but in the meantime if you could send me the prices for both options in a 27 inch length that would be great!