I would agree that a new MRI in six months is a good idea. Hemangiomas normally do not cause lucency in the bone so a follow-up is a good idea.
Hemangiomas are normally benign findings on an MRI examination. There are very rare circumstances these can be compressive but it does not sound like yours fit that description.
“Weakness and pain in neck, right arm, right shoulder and shoulder blade” could have many different diagnoses. Look up “Parsonage Turner syndrome” and “Thoracic outlet syndrome” on this website to understand some types of neuropathy similar to your complaints.
You mention previous schwannoma surgery. Where was this performed?
You mention neuropathy in the legs and a spondylolisthesis. These could be related or not. See the section under isthmic or degenerative spondylolisthesis to understand how nerve compression can be related to these disorders.
Donald Corenman, MD, DC is a highly-regarded spine surgeon, considered an expert in the area of neck and back pain. Trained as both a Medical Doctor and Doctor of Chiropractic, Dr. Corenman earned academic appointments as Clinical Assistant Professor and Assistant Professor of Orthopaedic Surgery at the University of Colorado Health Sciences Center, and his research on spine surgery and rehabilitation has resulted in the publication of multiple peer-reviewed articles and two books.