I have left my pittance in their wallet - is this safe and wise, or is it susceptible to getting hacked and stolen?

No, not safe or wise imo. Not only due to their taking their customers Steem and powering it up. I had coins I left on there that appear gone now from before their US ban. Not sure if they decided to keep them and nothing I can do about it, but when I sent a ticket in they acknowledged it was filed. Heard nothing for about a week then they sent me notification they were closing the ticket. Was only about 300.00 worth of coins, so writing it off as a 300.00 lesson never to leave coins on an exchange again.

You need to use YouTube on how to create paper wallets probably.

https://www.youtube.com/results?search_query=how+to+send+bitcoin+from+an+exchange+to+a+paper+wallet