Regarding a holdover seller, will my homeowner's insurance cover any damage or personal injury during the time of the eviction?
Question Details: How do I protect myself for this kind of event to happen?
Your homeowner's insurance should cover--at least within the terms of the policy (remember: insurance polices are essentially contracts; like any contract, they only cover what they say they do) so long as you 1) did not lie about or fail to disclose information on the application, and 2) take reasonable steps to remove them and protect yourself--like promptly bringing a legal action to remove the seller. (A failure to take reasonable steps to remove the holdover seller could void your coverate or allow the insurer to disclaim or deny a claim--you can't sit passively by while costs or damage increase.)
A landlord-tenant attorney should be able to bring a legal action to remove the seller. It is traditionally called an action "for ejectment" (though your state may have a different name for it); it is essentially eviction for nontenants.