Offer-- reinstate his authority or get a new one myself? Benifits or negatives?

If you are going to lease to a carrier, you don't need your own authority. There is no need to spend the money for the filing fees and cost of insurance unless you plan on operating under your own authority.

You can operate as a sole proprietorship. You probably have more owner operators operating as sole proprietorships than you do under a corporate structure. It is simpler as far as paperwork is concerned. I have several friends who still operate as a proprietorship. I also have friends who own corporations. There are benefits to both. Your best bet is to find a good CPA and/or corporate attorney, discuss your particular situation and objectives and have them advise you as to how you should proceed. I really prefer a corporate structure over a sole proprietorship. But, that is me and my situation. I save taxes by having the corporation.