Would a second bone graft be possible after one with less than ideal results?

No, this is not normal. But it can happen when the regenerated area does notheal properly, either by lack of postoperative care or poor suturing technique. I would recommend clinical and radiographic control to ensure that there is no infection of the regenerated area.

Without xrays and photos it is nearly impossible to provide you with a best answer. However there are many ways to reconstruct bone. Almost all of them work well in trained hands. One factor affecting the choice of graft is the amount of soft tissue available and exactly what portion of none...

There are different methods of socket grafting at tooth extraction site.  I usually place one or two dissolvable stitches at a ridge preservation graft like this but it is not always required.   When stitches are used, they are most commonly dissolvable and are gone...