Re: Guy with his pants' leg caught in the chain....
Welcome to the forum. Use the search feature at the top of the page and you'll have plenty to read on almost any question you can imagine.
As for legality, check the 'Laws and Legislation' section. Every state seems to have their own ideas about our funny little bikes so you'll need to check Missouri's or the town you plan to live in for specifics.
Women's bikes, or step through framed bicycles offer their own challenges to mounting an engine. There are rack mounts, over the rear wheel, both friction and chain drive.
Do some research and ask if you can't find answers.
Have fun, ride safe.
Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"