Your alk is good right where it is at 100. No more baking soda needed. Also, no PH Up or washing soda. Both of those will raise your ph AND your alk. You don't want your alk any higher. And, you're right about the Borax. It is used when you need to raise the PH but don't want to increase the alk.

It is a lot of information to learn at the beginning -- a pretty steep learning curve. You'll get it. You're doing great on clearing this pool!