I hope you have a fast recovery. .. rib pain sucks.

You are correct about how to purchase SPT..... Steem-Engine is the place. The price seems to be fluctuating allot so I would check the recent sales before purchase so your not buying at the current high point(not financial advise).

You can stake them in your steem-engine wallet. There will be a lock icon that you click to stake a specific coin and an unlock icon if you want to remove a stake.