As .COM is the natural domain extension for the United States based websites, it does get some priority in the’s search engine results (based on Google’s US datacenters) when competing against other countries’ domain extensions like .CO.UK, .CO.ZA, .COM.AU etc. However, .COMs don’t get automatic priority over other similar extensions like .ORG, .NET etc. that are also commonly used in the United States. All these domain extensions compete with .COMs on a level playing field.
Whether you can use an existing backlink profile for a new web project under the available domain depends on whether the link target of incoming links can be reconstructed. In order to analyze which content was provided under a domain in the past, you can find out on the Internet Archive Backlinks have no value if they lead to nowhere and this can even have a negative impact. They are possibly redirected to similar subpages or homepages using 301 redirect. In this case the most part of the link’s power is lost.

There’s an important distinction to make here between domain flipping and website flipping. The latter mainly refers to buying and selling full websites. By full websites, I mean websites that actually have content and more often than not have traffic and revenue. When buying and selling websites, the domain name matters less as the main value there is the content, traffic, revenue, history/reputation, sustainability and growth opportunities. The same can’t be said for domain names where you’re just selling “the name” and hence it’s all that really matters.