The concrete block walls will join in a T fashionm at a 90 degree angle. I want to tie the footer and the new concrete block into the existing old wall and footer.

If you are getting a permit, the issuing board should give you minimum standards. If not, for the footer, hammer drill 5/8" holes into the old footing and epoxy #5 rebar into the holes @90 degrees. Bend the rebar down into the new footing cavity. The wall is harder because the two are usually tied together. Some masons will cut out 1/2 a block and slide a new one in from the new wall. You can also use a concrete saw and cut slots into the abutting joints. As the wall is erected, slide in block reinforcement wire from the old wall to the new and make sure the mortar fills the cut. Don't forget to tie the top plate into the new wall by cutting out a section of the old plate, if possible and put in a connecting cross piece. A sawzall is the best tool for that. Good luck and let us know how it turns out.