I live in an area with clay soil and had a conifer tree adjacent to my block paved driveway.

Clay heavy ground can cause movement in dry summer. When the clay drys it shrinks. The tree and its roots will also have been a cause. To be sure have the damaged area taken up, dug out and a hardcore base put in which is compacted. The paving bricks then should be laid on sand/cement screed. Once laid silica sand brushed in to stop any lateral movement. You should have no further problems.

Yes .you might suffer from land heave .the ground might rise now due to the tree not removing as much water from the ground it will settle down after time

as long as most of the root is removed and a good depth of the clay removed which both cld be done at the same time then use type one to bring the levels back up to what clay was removed i.e the origanel hight then lay the drive on the type one the with the usual spec shld sort your problem out (dan)