Serial numbers can be found in different places, stamped into the rear dropouts, around or down the side of the seat tube, stamped into the headtube, under the bottom bracket area. Sometimes there are also manufacturer and date codes to add confusion. Also there is a web site where you can look up date codes on the components but I don't have that site's address handy.
Until you can upload some better detail pics can you say if the stays/tubes look like they are simply crimped/squeezed onto the rear dropout, or does it look like they are welded or brazed?
As to a possible bent frame or fork, when a bike hits something the top tube and down tube will often bend just behind the headtube lugs. Cracked or flaked off paint is often an indicator of this and is one of the things many of us keep an eye open for when looking at used bikes.