I am looking at a couple of companies that provide professional services in both healthcare and engineering services. I have started to run into professional corporations (in California) and professional llcs. I was wondering if anyone has found a good high level resource explaining these or any good legal advice on the subject. I am just starting to get an understanding and wondering how these fit with the search fund model as generally a searcher won't have the credentials to own a professional company. A couple of specific questions I have are listed bellow. Any high level help or a good online resource is appreciated.

When is a professional corporation/llc required? I have seen in California 2 speech therapy companies doing almost identical work and one is professional and one is not. Are there limitations on the non professional company buying the professional company in an asset sale.

Does providing two separate services prevent a company from being registered as a professional corporation/llc and is this a work around. This maybe the reason what was applicable to the speech therapy company above.

What are the best workarounds for the search fund model? I believe there are a few in healthcare with a medical provider entity and management entity with some payments between the entities. Does this work in other professional services?

What are the benefits of being a professional corporations? I believe the majors are malpractice liability and potentially tax, depending on the state.