A: US 20130320168 A1 "Mounting bracket for supporting an article" is a utility patent application, not a design patent. If you want to build a different machine (product) without infringing on it, you would have to make sure your product is not equivalent to this patent application or any other related patent or patent applications. You have to make sure that your product does not contain elements identical or equivalent to each claimed element found in each of the related patents. If you substitute any element of a claim, your substitution has to play a role substantially different from the claimed element. It is better to seek advise of a qualified patent attorney regarding infringement before embarking on a lot of expense building the product.
A: US 3456661 "Windproof umbrella" patent had effective filing date and priority date Feb 13, 1967. Patents are granted for 20 years, and accordingly this patent has expired long ago.
Once a patent is expired, the technology it covers falls in the public domain; that is, it is not owned by anybody, and everybody can use the technology without paying any assignment or licensing fee. So, there is no need to buy an expired patent.
The underlying public policy for granting a patent is that in exchange for a 20 year monopoly over the technology, the patent owner discloses the invention to the public. Once the 20 year monopoly period to exclude others is over, anybody can use the patent, and nobody owns it anymore. An alternative to patent is trade secret, where the inventor keeps the technology secret from everybody, and can gain the benefit of it as long as it remains secret. Since the people do not know about the technology, nobody take this technology further with research based on this invention. This is bad for sharing and advancing technology in general.