Honestly, I don't know the exact founder. But you could try looking in encyclopedias or specialized literature on science fiction and fantasy to find out.
The size of Fantasy and Science Fiction Magazine can be measured in different ways. In terms of page count, it can range from several dozen to over a hundred. Also, the physical dimensions and the amount of content it contains can contribute to its overall size.
Magazine of Fantasy & Science Fiction was founded way back in 1949. It has had a lasting impact on the world of speculative fiction, providing a platform for emerging and established writers alike.
There's also 'Lightspeed Magazine' which has a reputation for publishing a diverse range of science - fiction and fantasy stories, including works from emerging authors. It often has an interesting mix of different sub - genres within the broader categories of fantasy and science fiction, making it a great magazine to explore different styles and voices in these areas.
A fantasy and science fiction magazine often looks for engaging writing that combines adventure, mystery, and thought-provoking concepts. Good world-building and a compelling plot are essential too.