Just thought I'd add a follow up. Finally got the wax ring sealing properly (looks as if I somehow kept dropping it in off center!). So that was fine until this morning, when I tripped and fell onto the toilet, which now rocks back and forth with the greatest of ease. I believe I ripped one of the bolts out (just realizing now that I haven't checked the porcelain for a crack).
Still need to pull it up and investigate but really not looking forward to the encounter.