Amazon Basics Smart Box Spring Bed Base, 7-Inch Mattress Foundation - Twin Size, Tool-Free Easy Assembly

does it has legs?

Will this sit on top of the standard king size bed frame? Basically two frame rectangles that two box springs sit on?

What are the dimensions of the box it is delivered in

Is this a true 74" length? I have an antique sleigh bed and I bought one similar to this that measures 73.75" an it will not fit.